RCCPO
GRADUATION WORK
Purpose, device, technical characteristics and operating rules of mechanical ram preventers.
Completed:
Listener gr. KRSr-2
Ganberov.T.E
Checked:
Head of PC courses
Sorokin P.M.
Surgut 2011
1) Title page.
3) Appointment.
4) Device.
5) Specifications.
6) Rules of operation.
7) List of references.
Ram preventer
Purpose:
Designed for wellhead sealing during drilling, lowering and retrieval of tubing and other well completion and workover operations. Depending on the need, operating conditions, ram preventers can be single or double. This provides a variety of designs and the most rational use space for operation and maintenance.
Ram preventers provide:
· sealing the wellhead at operating pressure both on the drill string with the help of pipe and universal rams and in the absence of columns with the help of blind rams;
· Closing the rams of hydraulic preventers manually in the absence of control pressure;
· change of rams without removing the preventer from the wellhead and without dismantling hydraulic lines (for preventers with hydraulic control);
control of the open and closed position of the dies;
heating with a coolant (steam) of seals and dies at a temperature environment below 0°C.
Lids open hydraulically
· the pressure in the well creates an additional seal when the rams are closed;
· simplicity of a design provides, if necessary, easy replacement of all consolidations and the main details;
· all exposed metal sections of the preventer are resistant to hydrogen sulfide;
Manufactured in accordance with API 16A specifications.
The device and principle of operation of preventers:
Ram BOPs
For drilling on land, single-hull ram BOPs with a dual system for moving rams are used: hydraulic and mechanical without a hydraulic control system for their fixation.
By design, these preventers (Fig. XIII.3) are much simpler. Such a preventer consists of a body (2), inside which rams and covers with hydraulic cylinders (1) and (5) are placed. The body (2) is a box-section steel casting with a vertical through hole with a diameter D and a through horizontal rectangular cavity in which the dies are placed. Dies blocking the wellhead are completed for a certain pipe size. In the absence of drill pipes in the well, the mouth is blocked with blind dies.
The split preventer rams consist of a body (9), replaceable liners (11) and a rubber seal (10). The assembled die is mounted on the L-shaped groove a of the rod (7) and inserted into the preventer body. The body cavity is closed on both sides by hinged covers of hydraulic cylinders hinged on the body. The cover is fixed to the body with bolts (4).
Each ram is moved by a piston (6) of a hydraulic cylinder (8). Oil from the collector (3) through steel pipes and through a rotary nipple connection under pressure enters the hydraulic cylinders. The cavity of the preventer rams in winter time(at a temperature of -5°C and below) is heated by steam supplied to the steam pipelines. Piston with rod, cover and cylinders are sealed with rubber rings.
Technical characteristics of ram preventers:
Specifications for ram preventers are given in tab. 8.4-8.6.
The main indicators of the reliability of the ram BOP provide periodic testing of its operation by closing on the pipe, pressure testing with drilling fluid or water and opening, as well as the possibility of reciprocating the drill string along the length of the pipe under excessive pressure.
Reliability indicators of ram preventers are established by GOST 27743-88.
Specifications ram BOPs given in tab. 8.4-8.6.
Key Reliability Indicators ram preventer provide periodic checks of its functioning by closing on the pipe, pressure testing with drilling fluid or water and opening, as well as the possibility of walking the drill string along the length of the pipe under excessive pressure.
The preventer (Fig. XIII.2) consists of a cast steel body 7, to which the covers / four hydraulic cylinders 2 are attached to the studs. for fixing the dies 10 in the closed state of the hole G of the wellbore. To close the hole with rams, the fluid that controls their operation enters cavity A, under the action of which the piston moves from left to right.
The auxiliary piston 4 also moves to the right, and in the final position it presses the latch ring 5 and thereby fixes the plates 10 in the closed state, which prevents their spontaneous opening. To open the hole G of the barrel, you need to move the dies to the left. To do this, the control fluid must be supplied under pressure to cavity B, which moves the auxiliary piston 4 along the rod 6 to the left and opens the latch 5. This piston, having reached the stop in the main piston 3, moves it to the left, thereby opening the rams. In this case, the control fluid, located in the cavity £, is squeezed out into the control system.
The preventer rams 10 can be replaced depending on the diameter of the pipes to be sealed. The end of the dies around the circumference is sealed with a rubber cuff 9, and the cover 1 with a gasket //. Each of the preventers is controlled independently, but both rams of each preventer operate simultaneously. Holes 8 in the body 7 are used to connect the preventer to the manifold. The lower end of the housing is attached to the wellhead flange, and a universal preventer is attached to its upper end.
As you can see, a hydraulically controlled ram BOP should have two control lines: one to control the fixation of the position of the rams, the second to move them. Hydraulically controlled BOPs are mainly used in offshore drilling. In some cases, the lower preventer is equipped with rams with shearing knives to cut the pipe string in the well.
Universal preventers
The universal preventer is designed to improve the reliability of wellhead sealing. Its main working element is a powerful annular elastic seal, which, when the preventer is open, allows the drill string to pass, and when the preventer is closed, it is compressed, as a result of which the rubber seal compresses the pipe (kelly, lock) and seals the annular space between the drill string and the casing . The elasticity of the rubber seal allows the BOP to be closed on pipes different diameter, on locks and UBT. The use of universal preventers makes it possible to rotate and walk the string with a sealed annular gap.
The O-ring is compressed either by direct hydraulic force acting on the sealing element or by this force acting on the seal through a special annular piston.
Universal preventers with spherical sealing element and with conical sealing are manufactured by VZBT.
A universal hydraulic preventer with a spherical plunger seal (Fig. XIII.4) consists of a body 3, an annular plunger 5 and an annular rubber-metal spherical seal /. The seal has the form of a massive ring, reinforced with two-tee metal inserts for rigidity and wear reduction due to a more uniform distribution of stresses. Plunger 5 step shape with a central hole. Sealant / is fixed by cover 2 and spacer ring 4. The body, plunger and cover form two hydraulic chambers A and B in the preventer, isolated from each other by plunger cuffs.
When applying working fluid under plunger 5 through the hole in the preventer body, the plunger moves up and compresses the seal / around the sphere so that it expands towards the center and compresses the pipe inside the ring seal. In this case, the pressure of the drilling fluid in the well will act on the plunger and compress the seal. If there is no column in the well, the seal completely covers the hole. Upper chamber B serves to open the preventer. When oil is injected into it, the plunger moves down, displacing fluid from chamber A into the drain line.
Rotary preventers
A rotary preventer is used to seal the wellhead during drilling during rotation and reciprocation of the drill string, as well as during tripping and increased pressure in the well. This preventer seals kelly, lock or drill pipes, it allows you to raise, lower or rotate the drill string, drilling with backflushing, with aerated muds, with gaseous agent purge, with an equilibrium system of hydrostatic pressure on the formation, testing formations in the process of gas shows.
II. Technological part
1. Drilling oil and gas wells
Familiarization with the methods of manual bit feed, drilling with the bit feed regulator, training in drilling with a rotor.
When the bit is fed to the bottom, it is necessary to create a certain load on it. This operation is performed from the driller's console. The driller, using the so-called poker, lowers the tool, and then gradually, very slowly unloads the weight from the hook onto the bit. The load on the wireline is determined by the weight indicator. On the indicator, the division price can be different. When the traveling system is suspended, but the hook is not loaded, the weight indicator will show a value corresponding to the weight of the traveling system.
WOB should be equal to no more than 75% of the drill collar string weight. For example, there is a layout: 100 m of drill collar and 1000 m of drill pipes. Let the weight of the UBT string be 150 kN, and the weight of the BT string be 300 kN. The total weight of the BC in this case will be 450 kN. Approximately 2/3 of the weight of the drill collar must be fed to the slaughter, i.e. in this case 100 kN. To do this, the string is smoothly lowered by 9 m (the length of the stackable pipe) to the bottom. The moment of contact of the bit with the bottom is determined by the weight indicator: the arrow shows the decrease in weight on the hook. After that, it is necessary to very slowly release the winch and gradually load the bit until the arrow on the weight indicator shows 35 tons. on the indicator of mass, the oscillation of the arrow may not always be noticeable. It shows how many divisions the arrow on the weight indicator has passed, i.e. 3 Werner divisions are equal to 1 mass indicator division.
Rotors are used to transmit rotation to the drill string during drilling, to keep it suspended during round trips and auxiliary work.
The rotor is a gearbox that transmits rotation to a vertically suspended column from a horizontal transmission shaft. The rotor frame perceives and transfers to the base all the loads that occur during drilling and tripping operations. The internal cavity of the bed is an oil bath. At the outer end of the rotor shaft, on the key, there can be a sprocket or a half-coupling of the cardan shaft. When unscrewing the bit or to prevent rotation of the drill string from the action of an inactive moment, the rotor is locked with a latch or a locking mechanism. When the rotation is transmitted to the rotor from the engine through the winch, the rotation speed of the rotor is changed using the transmission mechanisms of the winch or by changing the sprockets. In order not to connect the work of the winch with the work of the rotor, in some cases, when rotary drilling, an individual drive to the rotor is used, that is, not connected with the winch.
2 inserts are inserted into the through hole of the rotor. Then, depending on the diameter of the pipes, the corresponding wedges are placed on the rotor, which are attached to four parallels. Parallels, in turn, are set in motion with the help of RCC (pneumatic rotor wedges), which are mounted on the opposite side of the rotor shaft. Using the pedal, which is located on the console, the driller raises or lowers the wedges.
When drilling begins, the wedges are removed from the rotor, thereby freeing the square hole of the liners. Then the so-called kelbush is fixed in this hole - a nut movably fixed on the leading pipe, which moves up and down along it. Further, with the help of the transmission, the necessary revolutions of the rotor are set, and it is driven from the driller's console.
Familiarization with the methodology of rational development of bits.
In order to rationally work out the bit, it is necessary to fulfill the penetration rate. As the bottomhole deepens, the rock cutting tool wears out, and in order to prevent wear from occurring ahead of time, it is necessary to observe the drilling mode.
Drilling mode includes rotor or downhole motor RPM, WOB and pump pressure (on the riser). So, for the correct development of the bit, the load on it should be more than 75% of the weight of the drill collar string. Overloading the bit can result in its premature wear or breakage of the cone, and underloading can lead to a drop in penetration. The rotor speed and the pressure on the riser are set according to the geological and technical line.
For rational development of the bit, it is necessary to feed it to the bottom without rotation and turn on the revolutions only after contact with the bottom. But before starting drilling, it is necessary to "run in" the bit for 30-40 minutes in order for it to run in. At the same time, the weight on the bit should be small - about 3-5 tons. When drilling with a turbodrill or a screw downhole motor, the bit is fed to the bottomhole already in rotation. In this case, you can either stop flushing and lower the bit to the bottom, or, without stopping the flushing, gradually load the bit to the required value.
Cone bit wear coding:
B - wear of weapons (at least one crown)
B1 - reduction in tooth height by 0.25%
B2 - reduction of the height of the teeth by 0.5%
B3 - reduction in tooth height by 0.75%
B4 - complete wear of the teeth
C - tooth chip in%
P - wear of the support (at least one cutter)
P1 - radial play of the cutter relative to the axis of the trunnion for bits
diameter less than 216 mm 0-2 mm; for bits larger than
216 mm 0-4 mm
P2 - radial play of the cutter relative to the axis of the trunnion for bits
diameter less than 216 mm 2-5 mm; for bits larger than
216 mm 4-8 mm
P3 - radial play of the cutter relative to the axis of the trunnion for bits
diameter less than 216 mm more than 5 mm; for bits larger than
216 mm over 8 mm
P4 - destruction of rolling elements
K - jamming of cutters (their number is indicated in brackets)
D - bit diameter reduction (mm)
A - emergency wear (the number of cutters and paws left is indicated in brackets)
AB (A1) - breakage and leaving the top of the cone at the bottom
ASh (A2) - in the breakdown and leaving the cone at the bottom
AC (A3) - leaving the paw at the bottom
Causes of abnormal wear of cone bits:
1) A large number of broken teeth:
Wrong choice of bit
Wrong bit break-in
Overspeed
Metal work
2) Strong wear on the diameter:
High speed
Squeezing of cones as a result of descent into the trunk of a reduced diameter
3) Cone body erosion:
Large consumption of flushing fluid
4) Excessive bearing wear:
Lack of stabilizer above the bit or between drill collars
High speed
Significant mechanical drilling time
5) Blockage of inter-crown spaces in cutters with drilled rock and solid phase:
Insufficient consumption of pancreas
The chisel is designed for harder formations
The bit was lowered into the bottom-hole zone filled with cuttings
6) Large number of lost teeth:
Cone body erosion
Significant mechanical drilling time
Performing basic work during open source software with the help of special equipment
The main unit in the implementation of the trip is a drawworks, which is driven by a power drive. For the best use of power during variable load hook lifting, winch drive transmissions or winch drive should be multi-speed. The winch must quickly switch from high speeds lifting to small ones and back, providing planned inclusions with a minimum expenditure of time for these operations. In cases of sticking and tightening of the string, the pulling force during lifting should be quickly increased. Switching speeds for lifting columns of different masses is carried out periodically.
Auxiliary winches and pneumobranchers are used to carry out work on pulling loads and screwing-on-screwing of pipes during the SPO.
Pneumatic breakers are designed to unfasten tool joints of drill pipes. The pneumobrancher consists of a cylinder in which a piston with a rod moves. The cylinder is closed at both ends with caps, one of which has a rod seal. A metal cable is attached to the rod on the opposite side of the piston, the other end of which is put on the machine key. Under the action of compressed air, the piston moves and rotates the machine key through the cable. The maximum force developed by the pneumatic cylinder at a compressed air pressure of 0.6 MPa is 50...70 kN. The stroke of the piston (rod) of the pneumatic cylinder is 740 ... 800 mm.
The complex of ASP mechanisms is designed for mechanization and partial automation of tripping operations. It provides:
combination in time of lifting and lowering the pipe string and an unloaded elevator with the operations of installing the stand on the stand, removing it from the stand, as well as screwing or screwing the stand with the drill string;
mechanization of the installation of candles on the candlestick and their removal to the center, as well as the capture or release of the drill pipe string by an automatic elevator.
ASP mechanisms include: lifting mechanism (raising and lowering a separately turned candle); gripping mechanism (capturing and holding an unscrewed candle during lifting, lowering, transferring it from the rotor to the candlestick and vice versa); placement mechanism (moving the candle from the center of the well and back); centralizer (holding the upper part of the candle in the center of the tower during screwing and screwing); automatic elevator (automatic capture and release of the BT column during descent and ascent); magazine and candlestick (holding unscrewed candles in a vertical position).
In the work of a complex of mechanisms such as ASP-ZM1, ASP-ZM4. ASP-ZM5 and ASP-ZM6 use the key AKB-ZM2 and the pneumatic wedge grip BO-700 (except for ASP-ZM6, for which the PKRBO-700 grip is used).
Preparing the pipe for dragging, installing the elevator on the rotor, removing it from the rotor, placing the pipes on wedges
Before pulling the pipes to the rig, it is necessary to make a visual inspection of the pipe body and threads. For an accurate analysis, a team of flaw detectorists is called in, who, using instruments, determine the suitability of pipes for use on a drilling rig. In addition, it is necessary, as necessary, to clean the threaded connections of the pipes, and then lubricate them with graphite grease or grease. After that, the pipes are delivered to the receiving bridges.
During drilling, the drill pipes are dragged one by one from the walkways to the rotor with the help of an auxiliary winch. Then the delivered pipe is screwed onto the string, and the bottomhole is further deepened by the length of the extended pipe.
Lifting and lowering drill pipes in order to replace a worn bit consists of the same repeated operations. Moreover, the machines include the operations of lifting the candle from the wells and the empty elevator. All other operations are machine-manual or manual requiring great physical effort. These include:
· when lifting: landing of the column on the elevator; unscrewing the threaded connection; installing a candle on a candlestick; empty elevator descent; transfer of links to the loaded elevator and lifting of the column to the height of the candle;
· at descent: withdrawal of a candle from behind a finger and from a candlestick; screwing a candle onto a column; lowering the string into the well; landing of the column on the elevator; transfer of links to a free elevator. Devices for gripping and hanging columns vary in size and load capacity.
Typically, this equipment is produced for drill pipes 60, 73, 89, 114, 127, 141, 169 mm in size with a rated load capacity of 75, 125, 140, 170, 200, 250, 320 tons. For casing pipes with a diameter of 194 to 426 mm, wedges in four sizes: 210, 273, 375 and 476 mm, designed for lifting capacities from 125 to 300 tons.
The elevator is used to capture and hold on the weight of the drill string (casing) pipes during tripping operations and other work in the drilling rig. Apply elevators various types, differing in size depending on the diameter of the drill or casing pipes, load capacity, constructive use and material for their manufacture. The elevator is suspended from the lifting hook with the help of slings.
Drill pipe wedges are used to hang the drilling tool in the rotor table. They are inserted into the conical bore of the rotor. The use of wedges speeds up work on tripping operations. V Lately automatic wedge grippers with a pneumatic drive of the PKR type are widely used (in this case, the wedges are inserted into the rotor not manually, but with the help of a special drive, which is controlled by the driller's console).
To lower heavy casing strings, wedges with a non-split body are used. They are installed on special pads above the wellhead. The wedge consists of a massive body that receives the weight of the casing pipes. Inside the body there are dies designed to capture the casing pipes and hold them in a suspended state. Raising and lowering the dies is carried out by turning the handle in one direction or another around the wedge, which is achieved by the presence of inclined correcting cutouts in the body, along which the rollers of the dies roll with the help of a lever.
Checking the lock thread, screwing the BT with the help of battery keys, reattaching and unfastening the lock connections with the help of UMK keys
In the process of SPO, it is necessary to repeatedly screw and unscrew the pipes. To simplify these operations, the drilling rig is equipped with special equipment. A special tool is used to make up and unscrew drill pipes and casing pipes. Various keys are used as such a tool. Some of them are intended for screwing, and others - for fastening and detaching the threaded connections of the column. Typically, lightweight all-round pre-make-up wrenches are designed for locks of one diameter, and heavy machine wrenches for fastening and unthreaded connections are designed for two, and sometimes more sizes of drill pipes and locks.
A chain wrench is used to turn the pipes manually. It consists of a handle and a chain with a fixing device. To capture the pipe, the chain wraps around it and is fixed on the top of the handle. Working with a chain wrench is very time consuming, so other equipment is used.
The automatic drilling tong of the battery is designed for mechanized screwing and screwing of pipes. The control panel is located at the driller's station and is equipped with two levers: one of them controls the movement of the key itself to the rotor and back and the pipe gripping mechanism, and with the help of the other, the pipes are screwed together. AKB greatly simplifies the process of open source software.
The operations of fastening and unfastening threaded connections of drill and casing strings are carried out by two UMK machine keys; while one key (delaying) is fixed, and the second (screwing) is movable. The keys are suspended in a horizontal position. To do this, metal rollers are strengthened on special “fingers” near the decks and a steel tether rope or one strand of a traveling rope is thrown through them. One end of this rope is attached to the key hanger and the other end is attached to a counterweight that balances the key and makes it easier to move the key up or down.
When lowering drill pipes and drill collars into the well, threaded connections should be tightened with machine and automatic wrenches, controlling the gap between the connecting elements and observing, according to the torque gauge, the value of the allowable torque established by the current instruction.
Inspection and measurement of BT and collar, installation of BT on a candlestick, screwing and unscrewing the chisels
Before starting drilling, it is necessary to inspect all pipes located on the drilling rig. Particular attention should be paid to checking threaded connections. The thread on drill pipes wears out during operation, so the length of the thread and its diameter must be measured periodically. This is done with the help of a tape measure. Permissible deviations in thread sizes are 3-4 mm. Special templates are used to check the size of pipes. The diameter of each template corresponds to a specific pipe diameter.
In the process of bottomhole deepening, the drill string is constantly growing. To do this, the drill pipe is dragged from the bridges with the help of an auxiliary winch to the rotor, is hooked by the elevator and then screwed onto the thread of the pipe set on wedges.
When it is necessary to lift the string, the pipes are unscrewed with candles to reduce the trip time. In this case, it is necessary to raise the upper end of the pipe above the rotor table, put it on wedges and fix it on the elevator. Then the column rises to the height of the candle, sits on the wedges, the candle is unscrewed with the battery key, wound up by the finger of the riding and semi-mounted worker and placed on the candlestick. After the necessary operations have been performed (bit change, BHA), the string is lowered with candles to the drilled depth.
Screwing on and unscrewing the cone bit is done with the help of an arm rest. The chisel is installed manually or with the help of an auxiliary winch in the armrest. Inside it there are 3 protrusions that go between the cutters. Then the chuck is placed on the rotor liners, and the bit is screwed onto the drill collar or sub. The paddle bit is mounted on the rotor using a special stand so that only one thread remains above the table, and then it is screwed onto the pipe.
Well flushing
Well flushing is the main part of drilling. How well the well will be brought to the design depth depends on the correctly selected solution formulation.
In the practice of drilling wells, various technological methods are used for the preparation of drilling fluids.
The most simple technology system(Fig. 7.2) includes a tank for mixing drilling mud components 1, equipped with mechanical and hydraulic mixers 9, a hydro-jet mixer 4, equipped with a loading funnel 5 and a slide gate 8, a centrifugal or piston pump 2 (usually one of the booster pumps) and manifolds.
According to this scheme, the preparation of the solution is carried out as follows. A calculated amount of the dispersion medium (usually 20-30 m3) is poured into the tank 1 and, using a pump 2, it is fed through the discharge line with a valve 3 through the hydraulic ejector mixer 4 in a closed cycle. Bag 6 with powdered material is transported by a mobile lift or conveyor to the platform of the tank, from where it is fed to platform 7 with the help of two workers and manually moved to funnel 5. mixing with the dispersion medium. The suspension is drained into a container, where it is thoroughly mixed with a mechanical or hydraulic mixer 9. The feed rate of the material into the ejector mixer chamber is controlled by a slide gate 8, and the vacuum in the chamber is controlled by replaceable hard-alloy nozzles.
The main disadvantage of the described technology is poor mechanization of work, uneven supply of components to the mixing zone, and poor control over the process. According to the described scheme maximum speed preparation of the solution does not exceed 40 m3 / h.
At present, in domestic practice, progressive technology for the preparation of drilling solutions from powdered materials is widely used. The technology is based on the use of commercially available equipment: a solution preparation unit (BPR), an external hydro-ejector mixer, a hydraulic disperser, a CS tank, mechanical and hydraulic mixers, and a piston pump.
To clean drilling fluid from cuttings, a complex of various mechanical devices is used: vibrating sieves, hydrocyclone sludge separators (sand and silt separators), separators, centrifuges. In addition, in the most unfavorable conditions, before cleaning from cuttings, the drilling mud is treated with flocculant reagents, which make it possible to increase the efficiency of the cleaning devices.
Despite the fact that the cleaning system is complex and expensive, in most cases its use is cost-effective due to a significant increase in drilling speeds, a reduction in the cost of regulating the properties of the drilling fluid, a reduction in the degree of complexity of the wellbore, and the satisfaction of environmental protection requirements.
As part of the circulation system, the devices must be installed in strict sequence. At the same time, the solution flow diagram must correspond to the following technological chain: well - gas separator - coarse sludge cleaning unit (vibrating screens) - degasser - fine sludge cleaning unit (sand and silt separators, separator) - solid phase content and composition control unit (centrifuge , hydrocyclone clay separator).
Of course, in the absence of gas in the drilling fluid, degassing steps are excluded; when using a non-weighted solution, as a rule, clay separators and centrifuges are not used; when cleaning heavy drilling fluid, hydrocyclone sludge separators (sand and silt separators) are usually excluded. In other words, each equipment is designed to perform quite specific functions and is not universal for all geological and technical drilling conditions. Therefore, the choice of equipment and technology for cleaning drilling fluid from cuttings is based on the specific conditions of drilling a well. And in order to make the right choice, you need to know the technological capabilities and basic functions of the equipment.
BHA and control of the drilling regime to combat the spontaneous curvature of the well
Technical and technological reasons lead to spontaneous curvature of the well due to the fact that they cause bending of the lower part of the drill string and misalignment of the bit axis relative to the center of the well. To exclude these processes or reduce the likelihood of their occurrence, it is necessary:
1. increase the rigidity of the bottom of the drill string;
2. exclude gaps between the centralizers and the borehole wall;
3. reduce WOB;
4. in case of drilling with downhole motors periodically rotate the drill string.
To fulfill the first two conditions, it is necessary to install at least two full-sized centralizers: above the bit and on the body of the near-bit drill collar (or on the RD). Installation of 2 - 3 full-size centralizers allows to increase BHA rigidity and reduce the chance of bending even without reducing WOB.
In some cases, pilot assemblies are used when the well is drilled in a stepped way: pilot - small diameter bit - extension - bit - reamer - drill collar - drill string. It is desirable to use collars of as large a diameter as possible. This increases the rigidity of the BHA and reduces the gaps between the pipe and the borehole wall.
2. Familiarization with pad drilling
A cluster of wells is such an arrangement when the mouths are close to each other on the same technological platform, and the bottoms of the wells are in the nodes of the reservoir development grid.
Currently, most production wells are drilled in clusters. This is explained by the fact that cluster drilling of deposits can significantly reduce the size of the areas occupied by drilling and then production wells, roads, power lines, and pipelines.
This advantage is of particular importance in the construction and operation of wells on fertile lands, in nature reserves, in the tundra, where the disturbed surface layer of the earth is restored after several decades, in swampy areas, which complicate and greatly increase the cost of construction and installation work of drilling and operational facilities. Pad drilling is also necessary when it is required to open oil deposits under industrial and civil structures, under the bottom of rivers and lakes, under the shelf zone from the shore and overpasses. A special place is occupied by cluster construction of wells in the Tyumen, Tomsk and other regions Western Siberia, which made it possible to successfully carry out the construction of oil and gas wells on backfill islands in a remote, swampy and populated region.
The location of the wells in the well pad depends on the terrain conditions and the proposed means of communication between the well pad and the base. Bushes that are not connected by permanent roads to the base are considered local. In some cases, bushes can be basic when they are located on highways. On local well pads, as a rule, they are arranged in the form of a fan in all directions, which makes it possible to have the maximum number of wells on a well pad.
Drilling and auxiliary equipment is mounted in such a way that when the drilling rig is moved from one well to another, the drilling pumps, receiving pits and part of the equipment for cleaning, chemical treatment and preparation of flushing fluid remain stationary until the completion of the construction of all (or part) of the wells on this well pad.
The number of wells in a cluster can vary from 2 to 20-30 or more. Moreover, the more wells in the pad, the greater the deviation of the bottoms from the wellheads, the length of the wellbore increases, the length of the wellbore increases, which leads to an increase in the cost of well drilling. In addition, there is a danger of meeting trunks. Therefore, it becomes necessary to calculate the required number of wells in a cluster.
In the practice of pad drilling, the main criterion for determining the number of wells in a pad is the total well flow rate and the gas factor of oil. These indicators determine the fire hazard of a well during open flowing and depend on the technical level of fire extinguishing equipment.
Knowing the approximate number of wells in the pad, they proceed to build a pad plan. A well pad plan is a schematic representation of the horizontal projections of the wells of all wells drilled from a given well pad. The pad plan includes a layout of the wellheads, the sequence of their drilling, the direction of movement of the machine, the design azimuths and offsets of the bottomholes. The task is completed by building a hive schema.
3. Running and cementing casing strings
After the required interval of rocks has been drilled, it is necessary to lower the casing string into the well. The casing string is used to strengthen the walls of the well, to isolate absorbing layers and aquifers.
The casing string is made up of pipes on socket, sleeveless threaded or welded joints and lowered into the well section by section or in one step from the mouth to the bottom. In one step, the string is lowered in case of sufficient stability of the walls of the well and the lifting capacity of the traveling system. When fixing deep wells, OK jointless threaded or welded connections should be used.
Intermediate OK are of several types:
1) solid - overlapping the entire wellbore from the bottom to the wellhead, regardless of the support of the previous interval;
2) liners - for fixing only the open interval of the well with overlapping the bottom of the previous OK by a certain amount;
3) secret columns - special QAP, which serve only to cover the interval of complications and have no connection with previous columns.
Sectional running of casing strings and fixing of wells with liners arose, firstly, as a practical solution to the problem of running heavy casing strings and, secondly, as a solution to the problem of simplifying the design of wells, reducing the diameters of casing pipes, as well as the gaps between the strings and the walls of the well, reducing the consumption of metal and plugging materials.
Technological equipment is used for successful cementing and for more efficient descent of the OK. Equipment includes the following devices: cementing heads, separating cementing plugs, check valves, column shoes, guide nozzles, centralizers, scrapers, turbulizers, shoe nozzles 1.2-1.5 m long with holes 20-30 mm in diameter in a spiral, annular hydraulic packers of the PDM type, staged cementing sleeves, etc.
CEMENTING HEAD
Cementing heads are designed to create a tight connection between the casing string and the injection lines of cementing units. The height of the cementing heads should allow them to be placed in the lifting links of the traveling system and, with appropriate equipment, used for cementing with casing string reaming.
SEPARATING CEMENTING PLUGS
Displacement plugs are designed to separate the cement slurry from the displacement fluid when it is forced into the annulus of wells. There are modifications of plugs, in which a thread for a plug is made in the upper part of the body on the inner surface, without which these plugs can be used as sectional plugs. The bottom plug is inserted into the casing just before the cement slurry is pumped in to prevent it from mixing with the drilling fluid, and the top plug is inserted after the entire volume of the cement slurry is pumped. The central channel in the lower plug is blocked by a rubber diaphragm, which breaks when landing on the "stop ring" and opens a channel for pushing the cement mortar.
CHECK VALVES
TsKOD check valves are designed for continuous self-filling of the casing string with drilling fluid when it is lowered into the well, as well as to prevent backflow of the cement slurry from the annulus and stop the separating cementing plug. Valves of the TsKOD type are lowered into the well with a casing string without a shut-off ball, which
Ram preventers are designed for sealing the wellhead in case of oil and gas production and open fountains on drill or casing pipes, as well as sealing the wellhead without tools. Sealing wellheads without tools have a solid section ram design.
The ram preventer consists of 3 main parts: a body, a hinged cover with a hydraulic cylinder and 2 rams 3.
The body of the preventer is box-shaped. The housing has a cylindrical hole in the vertical plane, and a rectangular hole in the horizontal plane, in the "pockets" of which the dies are placed. In the inner cavity of the housing, in its upper part, there is a specially processed annular surface, which provides sealing between the housing and the upper part of the die. The ram itself moves along the guide ribs, which provide a gap between the preventer body and the bottom of the ram.
On the outer surface of the body, around the vertical hole, there is a groove for the sealing ring and blind holes with threads for studs, which allow you to mount the preventer body on the crosspiece, and mount the over-prevention coil on top.
Side covers with hydraulic cylinders, which are mounted on swivel joints, are bolted to the body. Swivel joints allow hydraulic fluid to be supplied to the opening or closing chambers of hydraulic cylinders 8. Pistons with rods are placed in the hydraulic cylinders, which are connected to the rams with a "G" or "T" - shaped grip. The dies have the same and interchangeable bodies 1, to which, with the help of two bolts, liners are attached: deaf with a deaf seal, or pipe with a replaceable seal. The size of the pipe slips must correspond to the size of the pipes lowered into the well.
Requirements for preventers.
Ø Before installation, ram preventers, together with a cross and an over-prevention coil, must be pressure tested for tightness in workshop conditions on operating pressure according to the passport. No pressure drop allowed. The results of pressure testing are documented by the Act.
Ø After mounting the ram preventer at the wellhead, the preventer is pressurized to the operating pressure, but not more than the pressure of the column pressurization
Ø The preventers are fastened only with the use of prefabricated studs.
Need to know:
- ram preventers - single-acting shut-off devices, i.e. hold pressure only from below;
- ram preventers cannot be installed on the well “upside down” (i.e. in an inverted state), because they will not hold pressure from the well;
- ram preventers can be closed by hydraulic fluid pressure from the control station, auxiliary console and manually by handwheels.
-Closed preventer with handwheels, it is possible only by hydraulic fluid pressure, having previously unlocked the rams with the help of handwheels.
Ram BOPs
The preventer manufactured by VZBT (Fig. XIII.2) consists of a cast steel body 7, to which covers / four hydraulic cylinders are attached to the studs 2. in the cavity A cylinder 2 placed main piston 3, fortified on shto-ke 6. An auxiliary piston is located inside the piston 4, employee for fixing dies 10 closed hole G wellbore. To close the hole with dies, the liquid that controls their work enters the cavity A, under the influence of which the piston moves from left to right.
Auxiliary piston 4 also moves to the right, and in the final position he presses the latch ring 5 and thereby fixes the dies 10 in the closed state, which excludes their spontaneous opening. To open the hole G barrel, you need to move the dies to the left. To do this, the control fluid must be supplied under pressure to cavity B, which moves the auxiliary piston 4 by stock 6 to the left and opens the latch 5. This piston, having reached the stop in the main piston 3, moves it to the left, thereby revealing the plates. In this case, the control fluid located in the cavity J is squeezed out into the control system.
Dies 10 preventers can be replaced depending on the diameter of the pipes to be sealed. The end of the dies around the circumference is sealed with a rubber cuff 9, a lid 1 - laying //. Each of the preventers is controlled independently, but both rams of each preventer operate simultaneously. holes 8 in housing 7 are used to connect the preventer to the manifold. The lower end of the housing is attached to the wellhead flange, and a universal preventer is attached to its upper end.
As you can see, a hydraulically controlled ram preventer must have two control lines: one to control the fixation of the position of the rams, the second to move them. Hydraulically controlled BOPs are mainly used in offshore drilling. In some cases, the lower pre-ventor is equipped with rams with shearing knives to cut the pipe string in the well.
For drilling on land, mainly single-shell ram BOPs with a double system for moving the rams are used: hydraulic and mechanical without a hydraulic control system for their fixation. By design, these preventers (Fig. XIII.3) are much simpler. Such a preventer consists of a body 2, inside which are placed dies and covers with hydraulic cylinders 1 and 5. Frame 2 is a steel casting of box section, having a vertical through hole with a diameter D and a through horizontal rectangular cavity in which the dies are placed. Dies blocking the wellhead are completed for a certain pipe size. In the absence of drill pipes in the well, the mouth is blocked with blind dies.
Split preventer rams consist of a body 9, interchangeable liners 11 and rubber seal 10. The assembled die is placed on the L-shaped groove a rod 7 and inserted into the preventer body. The body cavity is closed on both sides by hinged covers of hydraulic cylinders / and 5, hinged on the body. The cover is bolted to the body 4.
Each plate is moved by a piston 6 hydraulic cylinder 8. Oil from manifold 3 through steel tubes and through a rotary nipple connection under pressure enters the hydraulic cylinders. The cavity of the preventer rams in winter (at a temperature of -5°C and below) is heated by steam supplied to the steam pipelines. Piston with rod, cover and cylinders are sealed with rubber rings.
Universal preventers
The universal preventer is designed to increase the reliability of wellhead sealing. Its main working element is a powerful annular elastic seal, which, when the preventer is open, allows the drill pipe string to pass, and when the preventer is closed, it is compressed, as a result of which the rubber seal compresses the pipe (lead pipe, lock) and seals the annular space between the drill pipe and casing columns. The elasticity of the rubber seal makes it possible to close the preventer on pipes of various diameters, on locks and drill collars. The use of universal preventers makes it possible to rotate and move the string with a sealed annular gap.
The annular seal is compressed either as a result of the direct effect of hydraulic force on the sealing element, or due to the effect of this force on the seal through a special annular piston.
Universal preventers with spherical sealing element and with conical sealing are manufactured by VZBT.
Universal hydraulic preventer with spherical plunger seal (Fig. XIII.4) consists of a body 3, ring plunger 5 and an annular rubber-metal spherical seal /. The seal has the form of a massive ring, reinforced with two-tee metal inserts for rigidity and wear reduction due to a more uniform distribution of stresses. Plunger 5 stepped shape with a central hole. Sealant / fixed by cover 2 and spacer ring 4. The body, plunger and cover form two hydraulic chambers in the BOP A and B, isolated from each other by plunger cuffs.
When the working fluid is supplied under plunger 5 through the hole in the preventer body, the plunger moves up and compresses the seal / around the sphere so that it expands towards the center and compresses the pipe inside the annular seal. In this case, the pressure of the drilling fluid in the well will act on the plunger and compress the seal. If there is no column in the well, the seal completely covers the hole. Upper chamber B serves to open the preventer. When oil is injected into it, the plunger moves down, displacing the liquid from the chamber A into the drain line. The seal expands and returns to its original shape.
The ring seal allows:
drag columns with a total length of up to 2000 m with locks or couplings with conical chamfers at an angle of 18 °;
pacing and turning columns;
repeatedly open and close the preventer.
The design of the preventer allows the replacement of the seal without dismantling it. The Universal Preventer can be controlled by either a manual plunger pump or an electrically driven pump. Closing time of universal preventer by hydraulic drive 10
Rotary preventers
A rotary preventer is used to seal the wellhead during drilling during rotation and reciprocation of the drill string, as well as during tripping and increased pressure in the well. This preventer seals kelly, lock or drill pipes, it allows you to raise, lower or rotate the drill string, drilling with backwash, with aerated muds, with gaseous agent purge, with an equilibrium system of hydrostatic pressure on the formation , to test the layers in the process of gas manifestations.
The main element of a rotating preventer (Fig. ХШ.5) is a seal 2, allowing you to drag the tool through its hole. The seal consists of a metal base and a rubber part, attached to the stem 4 with bayonet fittings and bolts. It is protected from turning by the key protrusions included in the cutouts of the barrel.
There are 7 preventers in the cartridge on two radial 5 and one emphasis 6 rolling bearing mounted barrel 4. Lip seals 3 serve to protect the preventer from getting liquid from the well into it between the barrel, body and cartridge. Fixation of the cartridge 7 in the case / is carried out by a latch 9, which opens under oil pressure supplied by a hand pump through a fitting 8.
