One of the main tasks after the drilling of a well is completed is to calculate its flow rate. Some people do not quite understand what a well flow rate is. In our article, we will see what it is and how it is calculated. This is necessary in order to understand whether it can provide the need for water. The calculation of the well flow rate is determined before the drilling organization issues you a facility passport, since the data calculated by them and the real one may not always match.
How to determine
Everyone knows that the main purpose of the well is to provide owners with high quality water in sufficient volume. This must be done before drilling is completed. Then these data must be compared with those obtained during geological exploration. Geological exploration provides information about whether there is an aquifer in a given place and how powerful it is.
But far from everything depends on the amount of water lying on the site, because a lot determines the correct arrangement of the well itself, how it was designed, at what depth, how high-quality the equipment is.
Master data for debit determination
To determine the productivity of the well and its compliance with the needs of water, the correct determination of the well flow rate will help. In other words, will you have enough water from this well for domestic needs.
Dynamic and static level
Before you find out what the well's water flow rate is, you need to get some more data. In this case, we are talking about dynamic and static indicators. What they are and how they are calculated, we will now tell.
It is important that the debit is a non-constant value. It depends entirely on seasonal changes, as well as some other circumstances. Therefore, it is impossible to establish exactly its indicators. This means that you need to use approximate figures. This work is required to establish whether a certain water supply is enough for normal living conditions.
The static level shows how much water is in the well without sampling. Such an indicator is considered by measuring from the surface of the earth to the water table. It must be determined when the water stops rising from the next fence.
Field production rates
In order for the information to be objective, you need to wait until the moment when the water is collected to the previous level. Only then can you continue your research. In order for the information to be objective, everything must be done consistently.
In order to determine the flow rate, we need to set dynamic and static indicators. Given that for accuracy it will be necessary to calculate the dynamic indicator several times. During the calculation, it is necessary to carry out pumping with different intensity. In this case, the error will be minimal.
How is the debit calculated?
In order not to puzzle over how to increase the flow rate of the well after it has been put into operation, it is required to carry out calculations as accurately as possible. Otherwise, you may not have enough water in the future. And if over time the well begins to silt up and the water yield decreases further, then the problem will only get worse.
If your well is about 80 meters deep, and the zone where the water starts is located at 75 meters from the surface, the static indicator (Hst) will be at a depth of 40 meters. Such data will help us calculate what is the height of the water column (Hw): 80 - 40 \u003d 40 m.
There is a very simple way, but its data is not always true, a way to determine the debit (D). To install it, it is necessary to pump out water for an hour, and then measure the dynamic level (Hd). It is quite possible to do this on your own, using the following formula: D = V*Hw/Hd - Hst. The intensity of pumping m 3 / hour is indicated by V.
In this case, for example, you pumped out 3 m 3 of water in an hour, the level dropped by 12 m, then the dynamic level was 40 + 12 = 52 m. Now we can transfer our data to the formula and get a flow rate of 10 m 3 / hour .
Almost always, this method is used to calculate and enter into the passport. But it is not very accurate, because they do not take into account the relationship between intensity and dynamic index. This means that they do not take into account an important indicator - the power of pumping equipment. If you use a more or less powerful pump, then this indicator will differ significantly.
With a rope with a plumb line, you can determine the water level
As we have already said, in order to obtain more reliable calculations, it is necessary to measure the dynamic level several times using pumps of different capacities. Only in this way will the result be closest to the truth.
To carry out calculations by this method, after the first measurement, you need to wait until the water level is restored to its previous level. Then pump out water for an hour with a pump of a different power, and then measure the dynamic indicator.
For example, it was 64 m, and the volume of pumped water was 5 m 3. The data that we received during the two samplings will allow us to obtain information using the following formula: Du = V2 - V1 / h2 - h1. V - with what intensity the pumping was done, h - how much the level fell compared to static indicators. For us, they amounted to 24 and 12 m. Thus, we received a flow rate of 0.17 m 3 / hour.
The specific well flow rate will show how the real flow rate will change if the dynamic level increases.
To calculate the real debit, we use the following formula: D = (Hf - Hst) * Du. Hf shows the upper point where the water intake begins (filter). We took 75 m for this indicator. Substituting the values \u200b\u200binto the formula, we get an indicator that equals 5.95 m 3 / hour. Thus, this indicator is almost two times less than that recorded in the well passport. It is more reliable, so you need to focus on it when you determine whether you have enough water or need an increase.
With this information, you can set the average flow rate of the well. It will show what the daily productivity of the well is.
In some cases, the construction of the well is done before the house is built, so it is not always possible to calculate whether there will be enough water or not.
In order not to solve the question of how to increase the debit, you need to demand that the correct calculations be done immediately. Accurate information must be entered in the passport. This is necessary so that if problems arise in the future, it was possible to restore the previous level of water intake.
YesNot
Nozzle diameter calculation
The diameter of the wellhead fitting for gas wells is determined by the formula:
Where - the diameter of the fitting, mm;
Consumption coefficient,;
Qg - gas flow rate, m3/day;
Pbur - buffer pressure, according to field data atm.
Calculate the diameter of the wellhead choke hole using formula (2.16) for well No. 1104:
Calculation of the minimum well flow rate that ensures the removal of the liquid phase
During the operation of gas wells, the most common complication is the ingress of the liquid phase (water or condensate). In this case, it is necessary to determine the minimum bottomhole flow rate of a gas well, at which there is still no accumulation of liquid at the bottomhole with the formation of a liquid plug.
The minimum flow rate of a gas well (in m3/day), at which a liquid plug is not formed at the bottomhole, is calculated by the formula:
Where - the minimum gas velocity at which a liquid plug is not formed, m / s;
Temperature under standard conditions, K,
Reservoir temperature, K,
Bottom hole pressure, MPa,
Atmospheric pressure, MPa,
Internal diameter of the tubing, according to the project = 0.062 m,
Coefficient of gas supercompressibility.
The minimum gas velocity at which no water lock is formed:
Minimum gas velocity at which no condensate plug is formed:
During the operation of gas wells, the most common complication is the ingress of the liquid phase (water or condensate). In this case, it is necessary to determine the minimum bottomhole flow rate of a gas well, at which there is no accumulation of liquid at the bottomhole with the formation of a liquid plug.
Using formulas (2.17-2.19), we calculate the minimum flow rates of gas condensate well No. 1104 of the Samburgsky oil and gas condensate field, at which condensate will not settle at the bottomhole:
The minimum flow rate at which water is taken out:
Or thousand m3/day.
Minimum gas velocity at which all condensate is brought to the surface:
Minimum flow rate for condensate removal:
Or thousand m3/day.
Comparing the obtained results, it can be noted that, under other unchanged conditions, the complete removal of condensate is possible at higher flow rates of a gas well than the complete removal of water.
Calculation of technological efficiency of sidetracking
The amount of additionally produced gas for the billing period due to drilling of the lateral horizontal wellbore No. 1104 in the productive formation is determined by the formula:
Where - the value of the actual oil produced by the well for the billing period, ;
The value of the theoretical (estimated) oil production from the well for the calculated period in the absence of a horizontal wellbore along the productive formation, .
Where - the flow rate of a well with a horizontal wellbore and a vertical one, ;
The flow rate of a vertical well, .
Correction factor taking into account compliance with additional gas production and depletion of recoverable reserves, n.u. For the first 2 years v=1;
The amount of additionally produced gas condensate is determined by the formula:
Where - the amount of additionally produced gas condensate for the billing period due to the drilling of a side horizontal wellbore, t;
Condensate gas factor, according to field data, kg/m3.
Calculation for 2 years according to the formulas (2.23-2.34):
In this section, the calculation of technological efficiency was made by drilling a horizontal wellbore in a vertical well. Comparison of the "actual" indicators of the development of the site by horizontal wells with the indicators of the base case, once again shows the undeniable advantage of using BGS in the development of low-productive reservoirs of relatively small effective thickness. Over the period of operation in natural mode for two years when using horizontal wells, additional production will be natural gas and tons of gas condensate, which is 9 times higher than these indicators over the base case.
Conclusions on the second section
1. Analysis modern methods Intensification of natural gas and gas condensate production showed the promise of using such methods as hydraulic fracturing and sidetracking in vertical and directional wells at the Samburgskoye oil and gas condensate field. Among these production stimulation methods, sidetracking is one of the most effective in the conditions of the Samburgskoye field.
2. The use of sidetracking technology in vertical and directional wells of the Samburgskoye oil and gas condensate field to transfer wells to horizontal wells will not only reduce drilling volumes, increase the flow rate and profitability of wells, but also use reservoir energy more rationally, due to lower drawdowns on the reservoir.
3. Based on the analysis of the production well stock and the density of residual mobile reserves of reservoir gas, candidate well No. 1104 was selected for sidetracking. For a larger implementation of this technology, it is recommended to conduct additional studies in order to identify other wells that are promising for sidetracking.
3. Technological calculation of the parameters of a candidate well according to the method of Aliyev Z.S. showed that the flow rate of the design well after sidetracking can increase by more than 10 times from 89.3 thousand m3/day to 903.2 thousand m3/day.
4. Calculations of the profile of well No. 1104 were performed. At the same time, “window cutting” in the EC at a depth of 2650 m was chosen as the technology of the drilling method, with a maximum angle of curvature of 2.0° per 10 m in the range of 2940 - 3103 m vertically and a horizontal section length of 400 m.
5. The calculation of the main parameters of the technological mode of the well operation made it possible to determine the diameter of the wellhead choke, the minimum gas velocities (m/s, m/s) at the bottomhole, ensuring the complete removal of water and gas condensate to the surface, as well as the minimum flow rates at which bottomhole liquid plugs (thousand m3/day, thousand m3/day). Under other constant conditions, the complete removal of condensate is possible at higher flow rates of a gas well than the complete removal of water.
6. The calculation of the technological efficiency of sidetracking shows the undeniable advantage of using this technology in the development of low-productive reservoirs of relatively small effective thickness. Over the period of operation in natural mode for two years, additional production will be natural gas and tons of gas condensate, which is 9 times higher than these indicators over the base option.
7. Thus, the performed calculations for the use of sidetracking at the Samburgskoye oil and gas condensate field have shown their effectiveness, and this technology can be recommended as a method for intensifying the production of natural gas and gas condensate at this field.
Works on the creation of a well on adjoining area provide for drilling, strengthening the head. Upon completion, the company that executed the order draws up a document for the well. The passport indicates the parameters of the structure, characteristics, measurements and calculation of the well.
Well Calculation Procedure
Employees of the company draw up an inspection protocol and an act of transfer to use.
The procedures are mandatory, since they provide an opportunity to obtain documentary evidence of the design's serviceability and the possibility of putting it into operation.
Geological parameters and technological characteristics are included in the documentation:
In order to check the correctness of the calculation, a test pumping of water is started at a high pump power. This improves the dynamics
In practice, for the accuracy of the calculation, the second formula is used. After receiving the flow rate values, an average indicator is determined, which allows you to accurately determine the increase in productivity with an increase in dynamics by 1 m.
Calculation formula:
Doud= D2 – D1/H2 – H1
- Dud - specific debit;
- D1, H1 - indicators of the first test;
- D2, H2 - indicators of the second test.
Only with the help of calculations, the correctness of the research and drilling of the water intake is confirmed.
Design characteristics in practice
Acquaintance with the methods for calculating a water well provokes the question - why does an ordinary user of a water intake need this knowledge? It is important to understand here that water loss is a single way to assess the health of a well in order to satisfy the needs of residents for water before signing the acceptance certificate.
To avoid problems in the future, proceed as follows:
- The calculation is carried out taking into account the number of residents of the house. The average water consumption is 200 liters per person. Added to this are the costs of economic needs and technical use. When calculating for a family of 4 people, we get the highest water consumption of 2.3 cubic meters / hour.
- In the process of drawing up the contract in the project, the value of the water intake productivity is taken at a level of at least 2.5 - 3 m 3 / h.
- After completion of work and calculation of the level of the well, water is pumped out, the dynamics are measured and the water loss is determined at the highest flow rate of the home pump.
Problems may arise at the level of calculating the well's water flow rate in the process of control pumping out by a pump owned by the contractor company.
The moments that determine the rate of filling the well with water:
- The volume of the water layer;
- The speed of its reduction;
- Depth ground water and level changes depending on the season.
Wells with a water intake productivity of less than 20 m 3 /day are considered unproductive.
Reasons for low flow rates:
- features of the hydrogeological situation of the area;
- changes depending on the season;
- filter clogging;
- blockages in the pipes that supply water to the top or their defloration;
- natural wear of the pump.
If problems are found after the well is put into operation, this indicates that there were errors at the stage of calculating the parameters. Therefore, this stage is one of the most important, which should not be overlooked.
In order to increase the productivity of the water intake, increase the depth of the well in order to open an additional layer of water.
Also, they use methods of pumping water experimentally, apply chemical and mechanical effects on the water layers, or transfer the well to another place.
test
4. Calculation of waterless well production rate, dependence of production rate on the degree of reservoir opening, anisotropy parameter
In most gas-bearing formations, vertical and horizontal permeabilities differ, and, as a rule, vertical permeability k is much less than horizontal k g. However, with low vertical permeability, the flow of gas from below into the area of influence of the imperfection of the well in terms of the degree of opening is also difficult. The exact mathematical relationship between the anisotropy parameter and the value of the allowable drawdown when the well penetrates an anisotropic reservoir with bottom water has not been established. The use of methods for determining Q pr, developed for isotropic reservoirs, leads to significant errors.
Solution algorithm:
1. Determine the critical parameters of the gas:
2. Determine the coefficient of supercompressibility in reservoir conditions:
3. We determine the density of the gas under standard conditions and then under reservoir conditions:
4. Find the height of the formation water column required to create a pressure of 0.1 MPa:
5. Determine the coefficients a* and b*:
6. Determine the average radius:
7. Find the coefficient D:
8. We determine the coefficients K o , Q* and the maximum anhydrous flow rate Q pr.bezv. depending on the degree of reservoir penetration h and for two different values anisotropy parameter:
Initial data:
Table 1 - Initial data for the calculation of the anhydrous regime.
Table 4 - Calculation of the anhydrous regime.
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Study of the motion of liquid and gas in a porous medium
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One of the characteristics of a drilled well is the rate of production from a drilled subterranean formation, or the ratio of volume to a certain time period. It turns out that the flow rate of a well is its performance, measured in m 3 / hour (second, day). The value of the well flow rate must be known when choosing the productivity of a well pump.
Factors determining filling rate:
Debit: calculation methods
The power of the pump for an artesian well must correspond to its productivity. Before drilling, it is necessary to calculate the volume required for water supply and compare the obtained data with the indicators of the exploration of the geological service in relation to the depth of the reservoir and its volume. The well flow rate is determined by a preliminary calculation of statistical and dynamic indicators relative to the water level.
Wells with a productivity of less than 20 m 3 /day are considered low-rate.
Reasons for a small well flow rate:
The calculation of the well flow rate is carried out at the stage of determining the depth of the aquifer, drawing up the design of the well, choosing the type and brand of pumping equipment. At the end of drilling, experimental filtration work is carried out with the indicators recorded in the passport. If an unsatisfactory result is obtained during commissioning, this means that errors were made in determining the design or selection of equipment.
Small well flow rate, what to do? There are several options:
Basic parameters for calculating the flow rate
The debit calculation formula is based on an exact mathematical calculation:
D \u003d H x V / (Hd - Hst), meter:
Well rate calculation example:
Substituting the data, we get the estimated flow rate - 5.716 m 3 / h.
For verification, a trial pumping with a larger pump is used, which will improve the dynamic level readings.
The second calculation must be performed according to the above formula. When both flow rates are known, the specific indicator is known, which gives an accurate idea of how much productivity increases with an increase in the dynamic level by 1 meter. For this, the formula is applied:
Dsp = D2 – D1/H2 – H1, where:
