RU2593287C1 - Method of step-by-step adjustment of gas production - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to gas industry and can be used to increase the gas recovery rate by step-by-step production regime control. Method involves assessing vapour phase, velocity and flow rate of gas phase, condensed water sampling, the assessment of condensed water - formation, condensation or technogeneous water on each well. Wells subject to be step-by-step adjustment, which is conducted based on excess of the evaluation values of the vapour phase and their design values by analytical expression are singled out. Wells with measured-current values of vapour phase exceeding their design values for the corresponding temperature and pressure conditions are subjected to step-by-step adjustment. When obtaining the current value of vapour phase corresponding to calculated formation temperature and pressure conditions, the well is left in the chosen mode of operation until the first winter extractions to allow replacement of water in proportion to pressure of gas. Discrete change of depression on the well arranged in the range of 5-20 % of the value of depression of winter extractions taken in 3-5 steps is taken as a tool of step-by-step control. Control of the modes is performed during summer extractions with obligatory hydro-metrical control of each stage.

EFFECT: technical result is avoiding premature formation water inflow into the well production, minimization of product flooding, increased the gas recovery rate as a whole, as well as increase of the gas extraction zones of production wells.

1 cl, 1 tbl, 3 dwg

Description

The invention relates to the gas industry and can be used to increase the gas recoverability through step-by-step regulation of production modes.

A known method of developing water-floating or gas condensate fields, including drilling wells and opening productive intervals with subsequent sampling of gas from production wells [RU 2107154 C1, IPC ЕВВ 43/18, ЕВВ 43/00 (1995.01), publ. 1999]. Pre-selection of gas from wells is carried out with a flow rate above the initial critical anhydrous flow rate. As a result, the breakthrough of the water cone into the well is recorded and the gas flow rate is allowed to change until the specified gas-water factor is reached, after which the gas is taken while maintaining the value of the established production level by changing the depression on the formation. The method allows to increase the final coefficient of gas recovery, to intensify the flow rates of wells for gas and to extend the period of profitable gas production.

The disadvantage is the wetting of the collectors with their subsequent destruction. Hence, an increase in the period of profitable gas production is unlikely, and the likelihood of a given well getting into equilibrium (shutdown) is significantly increased.

A known method of extracting water trapped in gas, according to which a gas reservoir or gas condensate field is used to select water, mainly from wells located near the initial gas content circuit [RU 2107154 C1, IPC ЕВВ 43/18, ЕВВ 43/00 (1995.01), publ. 1999]. Simultaneously with water, trapped (water) gas is extracted by lowering the reservoir pressure due to periodic intensive withdrawal of reservoir water and cyclic depressive effects on the bottom-hole zone of the reservoir at each stage of reservoir pressure, while the amount of depression is created based on the condition under which the gradient the hydrodynamic pressure at the site of the manifestation of the capillary end effect, in the bottomhole zone, would be higher than the capillary pressure gradient at this site, and The identity of the created depression in each cycle must satisfy the condition determined from the analytical expression.

The disadvantage is a significant increase in the possibility of breakthrough of additional water and blocking formation gas due to a disproportionate decrease in reservoir pressure in different parts of the reservoir.

The task to which the claimed technical solution is directed is to optimize the technological mode of well operation at the current stage of field development in order to prevent premature inflow of formation water and pinch gas reserves in the reservoir.

In the implementation of the technical solution, the problem is solved by achieving a technical result, which consists in eliminating premature formation water entering the well products, minimizing water cut, increasing the gas extraction coefficient as a whole, and also increasing the gas extraction zone of production wells, in particular the Cenomanian reservoir.

The specified technical result is achieved by the fact that the method of step-by-step regulation of gas production includes an assessment of the vapor phase, velocity and flow rate of the gas phase for each well, selection of droplet water, assessment of droplet water — formation, condensation or man-made, the selection of wells subject to step-by-step regulation, which is carried out on based on the excess of the estimated values of the vapor phase and their calculated values by the formula (W _0.6 = A / P + B), where A is a coefficient equal to the content of an ideal gas, B is a correction for non-ideal gas, P is pressure , MPa, with step-by-step regulation, wells with measured - current values of the vapor phase exceeding their calculated values for the corresponding thermobaric conditions are subject to step-by-step regulation; upon receipt of the current value of the vapor phase corresponding to the calculated reservoir thermobaric conditions, the well is left in the selected operating mode until the first winter selections with the provision of the displacement of water in proportion to the pressure of the gas, a step-by-step regulation tool is a discrete change in the depression on the well, lying in within 5-20% of the magnitude of the depression of the winter screenings, carried out in 3-5 stages, and the regulation of the regimes is carried out during the summer screenings with mandatory moisture metering of each stage.

By selecting depression (within 5-20% of the peak withdrawals), the regimes are regulated in several stages (steps) based on the assessment of measurements for each well, the vapor phase of the gas stream, its dynamic characteristics (speed and flow rate), selection of drop water and determination its chemical composition. The selection of wells subject to step-by-step regulation is determined with an estimated value of the vapor phase greater than the calculated one - W _0.6 = A / P + B (Bukachek's formula). “Step-by-step” regulation of the regimes is carried out in 3-4 stages during the summer selection with monitoring of the wells with a mandatory assessment of the vapor phase of the gas stream, its dynamic characteristics and the selection of drop water after each stage.

The causal relationship between the technical result and the essential features of the claimed technical solution is as follows.

To optimize the technological mode of operation of production gas wells, in order to prevent minimization of water flooding and increase the gas extraction zone, a method of "step-by-step" regulation with constant moisture control is developed. During its implementation, the gas flow is monitored (the presence of vapor, droplet phases), the rate of change of its dynamic characteristics. The results of the analysis of the measurements determine the presence or absence of additional water in the gas stream in the selection zone. Step-by-step regulation of the regimes is based on a change in the loads (depressions) on the wells (production facilities) not more than 5-20% of the previous value. The change of modes is controlled by hydrometric measurements and measurements of the dynamic characteristics (speed and flow rate) of the gas stream. The number of steps (steps) can be from three to five, depending on the magnitude of the vapor phase, which should correspond to the current reservoir thermobaric conditions. These adjustments are carried out during the summer selections.

Having received the vapor phase value corresponding to the calculated reservoir thermobaric conditions, the well remains in the selected mode until the first winter screenings. 1.5-2.0 months of well operation, in light mode, is enough to increase the withdrawal zone and displace water in proportion to the increase in gas pressure.

A method for stepwise controlling gas production is illustrated in FIG. 1-3 and table 1, which shows the results of changes in the vapor phase during production, step-by-step regulation of regimes and peak withdrawals, after step-by-step regulation of regimes (using production wells 1, 2, 3, 4 of cluster No. 1 as an example). In FIG. 1 (a, b) and FIG. 2 (a, b) using the example of production wells of PK-1 reservoir, the schemes of changing the vapor phase in the zones (Northern, Southern) before (04/07/2013) and after (07/17/2014) step-by-step regulation of the modes are considered. In FIG. 3 - typical dynamics of changes in the vapor phase during gas production and step-by-step regulation of regimes during the peak extraction period, using the example of one of the production wells as an example, typical dynamics of monitoring measurements 2013-2014 is shown. (before and after step-by-step regulation of modes).

A method for step-by-step regulation of gas production includes: background evaluation of moisture measurement (vapor phase), velocity and flow rate of a gas stream on the surface; selection of wells subject to step-by-step regulation; "Step by step" regulation; monitoring of wells after each "step-by-step" regulation with mandatory control of neighboring wells; if necessary - conducting a GIS-spectral neutron gamma-ray log-wide-range (SNGK-Sh) to identify intervals of super collectors, the presence of which in the wells was detected by moisture measurement.

Preliminarily, for evaluating the well’s production, background evaluations of moisture measurement, velocity, and flow rate of the gas flow on the surface at the wellhead, through a manhole, for a short period of time and without release of gas into the atmosphere, for example, in accordance with the method for express determination of moisture content in gas well products (RU 2255218 C1) using an IVA-6 B thermo-hygrometer (approved with technical and metrological characteristics given in the instruction manual (KING 7.772.001RE): GOST 12997-84; GOST 8.547-86GSI; GO ST 8.558-93 GSI; TU 4311-011-77511225-2005).

The vapor phase characterizes the current reservoir thermobaric conditions, is an indicator of watering the production site. The vapor phase of the produced gas depends on the degree of extraction and the proximity of water in the extraction zone and is in linear relationship with them, characteristic of the reservoir. The dependence on the degree of selection is confirmed by the increase in the vapor phase in time. The vapor phase carries information about the presence of water in reservoir thermobaric conditions.

According to the results of background measurements, evaluate for each well:

vapor phase;

chemical composition, type of carried out drop liquid (reservoir, condensation, technogenic);

speed and flow rate.

The criterion for selecting wells for step-by-step regulation of the regimes is the excess of the measured value of the vapor phase over the calculated value for the corresponding thermobaric conditions at any stage of development. The calculated value of the vapor phase (algorithmic criterion for the presence or absence of additional water) corresponding to thermobaric conditions is calculated by the Bukachek formula (A.I. Gritsenko, Z.S. Aliyev, OM Ermilov, VV Remizov, G.A Zotov, Guidelines for Well Research, Moscow, Nauka, 1995. - P. 64-71):

Where:

W _0.6 is the calculated value of the vapor phase (g / m ³ ) at a gas density of 0.6 kg / m ³ _;

A is a coefficient equal to the content of an ideal gas;

P is the pressure, MPa;

B - correction for the imperfection of natural gas.

A change in the vapor phase that does not correspond to the thermobaric conditions makes it possible to predict additional water in the extraction zone until the gas-venting intervals are blocked by additional water. The presence of additional water is estimated by the difference between the calculated and measured vapor phases.

Then, a breakdown of the existing well stock is carried out, which includes the allocation of the entire active well stock operating:

without pulling up additional water, in which the estimated value of the vapor phase is equal to or less than the calculated one, that is, the value of the vapor phase corresponds to the current thermobaric conditions; not subject to step-by-step regulation;

with pulling up additional water, in which the measured value of the vapor phase is larger than the calculated one, that is, the value of the vapor phase does not correspond to thermobaric conditions; subject to "step by step" regulation.

Taking into account the breakdown of wells, the optimal operating mode of production wells is selected that minimizes or completely eliminates premature flooding of wells and pinching of gas reserves due to forced advance of formation water.

The tool of "step-by-step" regulation of regimes is a discrete change in the load (depression) on the well (production object). The discreteness value depends on the features of the deposits, the estimated values of the vapor phase and lies within 5-20% of the regime of winter (peak) selections. A mode is a particular load (depression) on a formation in order to optimize production. Depression is the pressure difference between the reservoir and bottomhole pressures, which ensures the flow of gas into the perforations (into the column).

“Step-by-step” regulation of the regimes is carried out in 3-5 stages, in the summer selection mode, with the mandatory monitoring of the vapor phase, speed, gas flow rate and drop water withdrawal after each stage.

According to the results of monitoring studies, after "step-by-step" regulation, the wells are identified:

- in which water was cut off due to an increase in gas pressure in the extraction zone;

- having in their context “supercollector” (current or future watering intervals), in which you need to set your own technological regime, different from others, to eliminate the avalanche-like pulling up of additional water.

- intensively working with additional water, with the content of the reservoir, are not subject to "step by step" regulation, but only to other - geological and technical measures for water isolation.

Table 1 shows the following indicators. The measurements were carried out with the PIR-RG-601 device, an ultrasonic gas flow meter, designed to measure the volumetric (mass) flow rate of liquids and gases flowing through the pipeline.

Qg - gas flow rate, tm ³ / day (column 4);

Qg - (PIR) estimated measurements of gas flow rate during the production of moisture measurements tm ³ / day (column 5);

V is the gas flow velocity, m / s (column 6);

Q / V - mass of gas per unit of speed - estimated value of the recovered gas; current development indicator (column 7);

RBUF. - pressure at the mouth, atm. (column 8);

Wg - estimated vapor phase, g / m ³ (column 9), measurements were carried out with an IVA-6B thermohygrometer.

According to the studies dated 07/04/2013, the high values of the vapor phase that do not correspond to the thermobaric conditions distinguish the wells: No. 1 (1.7 g / m ³ ); removal of a dropping liquid with a mineralization of 8.1 g / l with a reservoir content of up to 35.5% and condensation up to 64.5% (see Fig. 2a) —well. Number 3.

Studies from 07/08/2014 - 07/17/2014 were carried out after a "step-by-step" load reduction in wells with high current values of the vapor phase (well No. 1-1.7 g / m ³ ) and the removal of mixed water with formation content (well No. 3-up to 35.5%) with the aim of cutting off produced water.

As a result of step-by-step regulation of depression in wells (with a background value of the vapor phase of more than 0.5 gm ³ ) in these wells, as well as in neighboring ones, the value of the vapor phase is reduced to 0.5 g / m ³ (No. 1); absence of formation water in well No. 3.

As a result of monitoring measurements (07/17/2014) in all wells of the cluster No. and the southern zone, the values of the vapor phase correspond to the current thermobaric conditions (see Fig. 2b). The value of the vapor phase in the southern zone is in the range 0.46-0.55 g / m ³ .

Wells that work intensively with additional water are wells in which the difference between the calculated and measured values of the vapor phase reaches 50% or more. In the example set forth in table No. 1, such a vapor phase value (1.7 g / m ³ ) marked well No. 251 (measured from 07/04/2013), relative to neighboring wells and background measurements (Fig. 2a). Long-term operation of the well with such a vapor phase value leads to the destruction of the rock skeleton, the creation of sand plugs in the wellbore, flooding of the gas extraction interval, and the spreading of the water front into neighboring wells to zones with abnormally low reservoir pressures (ANP).

The selection of dropping liquid from the gas stream with the UGMK-4 device (columns 9, 10) is carried out in order to determine the chemical composition and type of water. The chemical composition of water is determined, in the field, by a KSL conductometric laboratory multitest, designed to measure the electrical conductivity of liquids (TU 4215-102-45444533-05). The measurement results are presented in terms of electrical conductivity (SEC) and total salt content in terms of sodium chloride NaCl. Mineralization is determined by NaCl (%). The content of NaCl determines the type of water: condensation type (K) - NaCl≤1.0 g / l; reservoir type (P) - NaCl≤18.0 g / l; technogenic type (T) - NaCl> 24.0 g / l.

The composition of other elements, in the conditions of the Far North, can be neglected due to their meager content

Example 1: in column 11 of the table. No. 1 marked type of water - 100K. This means that the water sample contains 100% condensation liquid with a total salinity (NaCl) of 0.35 g / l of column 10.

Example 2: in column 11 the type of water is 35.5P + 64.5K - this means that the water sample contains 35.5% of produced water and 64.5% of condensation water with a total mineralization (NaCl) of 8.1 g / l (column 10).

All measurements are carried out using a mobile laboratory, without stopping the wells and the release of gas into the atmosphere. Sampling is carried out on the surface through a socket for installing a manometer (VI 15) in the wellhead piping system. Measurements are taken at a long-term stable mode of operation of the well.

Evaluation of the quality of the gas stream (the moisture content of the gas flow of the production well for the presence of water in different phase states: vapor phase and droplet phase) is carried out through samplers using indicator methods.

Measurements with an IVA-6B thermohygrometer to assess the content of the current value of the vapor phase, which carries information about the presence of water (in this stable physical condition), in the sampling zone and at the mouth, in the selected gas sample, while obtaining a value close to reliable .

Then, in the changed production conditions, repeated studies of this well are carried out in 0.5-1 year with the same set of equipment. Get the value of the vapor phase in the sampled gas, close to a reliable value.

To obtain an estimated value of the vapor phase close to a reliable value, a site acquisition technique is used, i.e. 4-5 repeated measurements with a variable thousandth. Then, leaving the hundredth digit unchanged, they attribute it to the obtained value - “the value of the vapor phase value in the on-line mode” (until the fourth digit changes, the third digit remains stable).

All unstable states of water, as a result of the pressure difference (ΔР = Rpl-Rzab), are removed from the well by a gas stream in the form of a drop, which we take on the surface of UGMK-4 to determine the salinity and type of water, which are determined at the assessment level. Having the result, the production operator himself, selectively, selects water in the same way and determines the chemical composition in his laboratory.

In table 1, according to the results of moisture metering from 04/04/2013, in production wells No. 1, 2, 3, 4 of cluster No. located in the southern part of PK-1 reservoir (Fig. 2a), with background values of the vapor phase in this zone 0.45 -0.5 g / m ³ , 2 wells are distinguished:

No. 1 - a high value of the vapor phase - 1.7 g / m ³ that does not correspond to the current thermobaric conditions of the PK-1 formation, compared with wells of other clusters, in which, under current thermobaric conditions, the value of the vapor phase (outside the selected zone) varies from 0.45- 0.5 g / m ³ .

No. 3 - with a slight excess of the background value of the vapor phase (0.57 g / m ³ ), the formation water contains up to 35.5% in the composition of the droplet phase, and 8.1 g / l with NaCl mineralization.

Selection of the optimal regime in order to reduce the vapor phase in the well. No. 1 and the elimination of water inflow of produced water in the well. No. 3, carried out in 4 stages with subsequent monitoring of the quality of the gas stream and its dynamic characteristics. As a result, a decrease in the vapor phase in well No. 1 was achieved; 3 to values of 0.47-0.49 g / m ³ (Fig. 2b, Table 1, measurements from 07/17/2014) and cutoff of produced water in the well. No. 3, confirmed by sampling device UGMK-4. A correctly selected regime allowed increasing gas extraction during peak (winter) withdrawals, with even lower values of the vapor phase (0.41-0.46 g / m ³ monitoring dated 10/12/2014). When determining the magnitude of depression (and the number of stages), we proceeded from the estimated values of the vapor phase, its change (decrease or increase) relative to the previous measurement. The change in depression was within 5-20% of the peak selection regime. Similar results are shown on the example of production wells in the Northern zone of the PK-1 reservoir, in which the measured vapor phase values before step-by-step regulation varied from 0.7 to 1.2 g / m ³ , with background vapor phase values of 0.44-0.52 g / m ³ (Fig. 1a - background measurements from 07/04/2013). After adjusting the regimes in the wells, a decrease in the vapor phase to values of 0.42-0.52 g / m ³ was achieved (Fig. 1b - monitoring dated 07/17/2014).

In FIG. Figure 3 shows the typical dynamics of the change in the vapor phase during gas production, step-by-step regulation of regimes and during peak withdrawals in the form of graphs for the period of exploitation of the PK-1 deposit from September 22, 2009 to October 12, 2014, based on the results of periodic background measurements of the entire fund wells for PK-1 deposits and monitoring of wells allocated for step-by-step regulation of the modes, according to the background results. From the graph (as an example of one of the wells) it is seen that at the initial stage of operation, under current thermobaric conditions, the minimum value of the vapor phase (0.18 g / m ³ ) was noted. The appearance of additional water in the well selection zone was recorded by an increase in the vapor phase to values of 0.7 g / m ³ 06/15/2013 relative to the background values of 0.4-0.5 g / m ³ . Step-by-step regulation of the regime in this well was carried out in 4 stages in 2013, during monitoring studies after each stage. During the peak sampling period (September 28, 2013, June 19, 2014, October 12, 2014), an unchanged vapor phase value (0.46 g / m ³ ) was noted (with an increase in flow rate). As a result, an increase in flow rate was achieved with the displacement of additional water. As a result of step-by-step regulation, a production level of 557-564 tm ³ / day was achieved with a vapor phase value of 0.46 g / m ³ slightly exceeding the previous one (420 tm ³ / day dated 06/15/2013) with a vapor phase value of 0.7 g / m ³ .

Thus, with the help of step-by-step regulation of the modes according to the results of moisture measurement, the displacement of additional water from the zones of production wells extraction is achieved, the water inflow of produced water is eliminated, the technological mode with a certain increase in production is optimized.

Claims (1)

A method of step-by-step regulation of gas production, including an assessment of the vapor phase, velocity and flow rate of the gas phase for each well, selection of droplet water, estimation of droplet water - reservoir, condensation or man-made, the selection of wells subject to step-by-step regulation, which is carried out on the basis of exceeding the estimated values of the vapor phase and their calculated values by the formula
W _0.6 = A / P + B,
where A is a coefficient equal to the content of an ideal gas;
B - correction for non-ideal gas;
P - pressure, MPa,
in this case, wells with measured - current values of the vapor phase exceeding their calculated values for the corresponding thermobaric conditions are subject to step-by-step regulation; upon receipt of the current value of the vapor phase corresponding to the calculated reservoir thermobaric conditions, the well is left in the selected operating mode until the first winter withdrawals ensuring water is displaced in proportion to the gas pressure, a discrete change in depression to the well lying in the limit is adopted by the step-by-step regulation tool x 5-20% of the amount of depression of winter selections, held in 3-5 stages, and modes of regulation is carried out during the summer heats with mandatory vlagometricheskim control of each stage.

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