RU2597897C1 - Procedure for elimination of annulus circulation - Google Patents

Procedure for elimination of annulus circulation Download PDF

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RU2597897C1
RU2597897C1 RU2015136665/03A RU2015136665A RU2597897C1 RU 2597897 C1 RU2597897 C1 RU 2597897C1 RU 2015136665/03 A RU2015136665/03 A RU 2015136665/03A RU 2015136665 A RU2015136665 A RU 2015136665A RU 2597897 C1 RU2597897 C1 RU 2597897C1
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water
well
injection
aquifer
modified
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RU2015136665/03A
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Russian (ru)
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Раис Салихович Хисамов
Вадим Валерьевич Ахметгареев
Венера Асгатовна Таипова
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Открытое акционерное общество "Татнефть" им. В.Д. Шашина
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Abstract

FIELD: oil and gas industry.
SUBSTANCE: invention relates to oil industry and can be used in production and injection wells, in which there is inflow or absorption of fluid in above- or underlying horizons. Method involves selection of production or injection well with inflow or absorption in above -or underlying aquifers relative to operated oil-bearing strata, well shutdown, pumping thereinto composition for restraint of water influx or water absorption, start of well in operation. Composition for limiting water influx or water absorption is modified with water, wherein composition and ion concentration of dissolved salts is determined from reduction of permeability of core aquifer at least 10 times when pumping one porous volume of core at formation temperature, wherein reduction of permeability is a result of precipitation of salts during reaction of modified water with brine water-bearing layer, in well is injected modified water heated to temperature of 40-100 °C at bottom and with flow rate of 0.5-1.0 of maximum capacity of water-bearing layer, total volume of injection is defined as 20-300 m3 per 1 m effective thickness of water-bearing layer, if necessary, preventing precipitation of salts in pumping equipment and pipes in first 2-5 % of total volume of injected modified water inhibitors are added, operations on injection of modified water are repeated at new flooding of production well with water from water bearing horizon at least to 95 % or higher intake capacity of injection well to a value greater than maximum capacity of productive oil formation.
EFFECT: high efficiency of elimination of annulus circulation in production and injection wells and prolonged effect.
1 cl, 1 dwg

Description

The invention relates to the oil industry and can find application in production and injection wells, in which there is an influx or absorption of fluid in the higher or lower horizons.

A known method of isolating water inflows or absorption zones in a well, comprising sequentially injecting into the well a gelling material based on nepheline, a separator and an aqueous solution of hydrochloric acid of 14-16% concentration, where a dispersion of syenite alumina alkali concentrate is used as a gelling material. Spend technological exposure 2 hours. At the same time, isolation of water inflows and absorption zones occurs in the well (RF patent No. 2224102, class ЕВВ 43/22, publ. 02.20.2004).

Closest to the proposed invention in technical essence is a method of repair and insulation work in a well, comprising supplying to the isolation zone, at least in one step, until its saturation, a gel-forming material, which is used as a pulp of a syenite alumina alkali concentrate in a solution of calcium chloride with a specific gravity of not more than 1.2 g / cm 3 with a volume ratio of 1: 1, with a delivery rate of at least 3 l / s and a subsequent supply of hydrochloric acid of 27% concentration with a delivery rate of 2 -6 l / s, with a weight ratio of gel-forming material and hydrochloric acid 1: 1 (RF patent No. 2271445, CL ЕВВ 43/32, publ. March 10, 2006 - prototype).

A common disadvantage of the known methods is the low efficiency of isolation and the short duration of the effect. The injection of gel-forming compounds and subsequent acid treatment is a rather complicated technology in which the optimal concentration and injection volumes of compounds can be selected only with accurate data on the bottom-hole formation zone, above and underlying layers and the state of the well. The implementation of these methods showed that it is possible to obtain a negative effect, and with successful isolation, the duration of the effect does not exceed 3 months.

The proposed invention solves the problem of increasing the efficiency of elimination of annular circulation in production and injection wells and increasing the duration of the effect.

The problem is solved in that in a method for eliminating annular circulation, which includes selecting a producing or injection well with inflow or absorption into the higher or lower aquifers relative to the operating oil-bearing formation, shutting the well, injecting composition to limit water inflow or water absorption, putting the well into operation , according to the invention, as a composition for limiting water inflow or water absorption, modified water is used - water, concentration and ionic composition of dissolved salts which is determined by laboratory studies of reducing the permeability of the core of the aquifer no less than 10 times when pumping one pore volume of the core at reservoir temperature, while the decrease in permeability is the result of salt precipitation during the reaction of modified water with produced water of the aquifer, modified water is pumped into the well, heated to 40-100 ° C and the temperature at the bottom at a rate of 0.5-1.0 of the maximum injection capacity of the aquifer, the total amount of injection is determined as 20-300 m 3 per 1 m e the effective thickness of the aquifer, if necessary, to prevent the precipitation of salts in the pumping equipment and pipes in the first 2-5% of the total volume of injected modified water, inhibitors add, the procedure for injecting modified water is repeated with a new flooding of the producing well with water from the aquifer to at least 95 % or with increasing injectivity of the injection well to a value greater than the maximum injectivity of the productive oil reservoir.

SUMMARY OF THE INVENTION

The efficiency of eliminating annular circulation and the duration of the effect is significantly affected by the degree of decrease in the permeability of the aquifer during the injection of a waterproofing composition and the penetration depth of this composition. Existing technical solutions do not fully allow efficiently and for a long period to eliminate annular circulation. The proposed invention solves the problem of increasing the efficiency of elimination of annular circulation in production and injection wells and increasing the duration of the effect. The problem is solved as follows.

In FIG. 1 is a schematic representation of a well, oil and aquifer. Designations: 1 - productive oil reservoir, 2 - aquifer, 3 - non-reservoir, 4 - well, 5 - casing, 6 - cement stone, 7 - perforations, 8 - section of the production string with no cement stone.

The method is implemented as follows.

The reservoir site is represented by two layers: oil-saturated 1 and water-saturated 2, separated by a layer of non-reservoir 3 (Fig. 1). Well opens these layers. 4. Consider the cases of producing and injection wells separately.

Producing well. Well 4 is flooded, and it has been established that the cause of flooding is annular circulation from the aquifer 2 (for example, the lower one) due to a violation of the casing 5 and / or cement 6. For example, this can be determined by the different specific gravity of the withdrawn water relative to the specific gravity of the reservoir reservoir water 1.

Preliminary laboratory tests are carried out on the core at reservoir temperature for incompatibility of the reservoir and the water intended for injection. Moreover, water is selected (we will conventionally call it modified) with an ionic composition and / or salt concentration that is different from the formation water, such that when mixed with the produced water of the aquifer 2, salts precipitate. The volume of sediment deposited should be sufficient to reduce the permeability of the aquifer 2 by at least 10 times when pumping one pore volume of the core. According to studies, with a decrease in permeability of less than 10 times, the efficiency of elimination of annular circulation is practically absent, because the influx of water from the aquifer 2 remains quite high compared with the influx of oil or liquid from the reservoir 1.

After selecting the composition of such modified water, it is pumped heated to a temperature of 40-100 ° C at the bottom through pipes with minimal heat loss to the external environment (for example, a thermal case). This operation must be carried out for the greatest penetration of modified water into the aquifer 2. High temperature allows the mixing of modified and produced water to significantly reduce the rate of sedimentation. In this case, as the modified water advances and its cooling, the rate of sedimentation will increase. According to studies, in the reaction of modified water with a temperature of less than 40 ° C in most cases premature precipitation of salts occurs, whereas injection at a temperature of more than 100 ° C is not economically viable due to the high cost of heating the water. A specific temperature in the range of 40-100 ° C is determined preliminarily by laboratory tests and calculated depending on the injection rate and heat loss during injection on thermal hydrodynamic models.

The flow rate of modified water is defined as 0.5-1.0 of the maximum injectivity of the aquifer 2. According to the calculations, when the flow rate is less than 0.5 of the maximum injectivity of the aquifer 2, water cools faster than penetration into the reservoir, which reduces the effectiveness of waterproofing. If the maximum injectivity of the aquifer 2 is exceeded, both the well and formations 1 and / or 2 may be disturbed (for example, hydraulic fracturing).

The total injection volume of modified water is calculated as 20-300 m 3 per 1 m of the effective thickness of the aquifer 2. Calculations show that for most reservoirs this volume is sufficient to eliminate annular circulation by galvanizing the aquifer 2. Large injection volumes of more than 300 m 3 / m do not desirable due to a possible decrease in the productivity of oil reservoir 1 due to the arrival of injected modified water into it. Volumes of less than 20 m 3 / m do not penetrate deep enough into the aquifer 2. A more specific value of the injection volume is determined by the results of hydrodynamic modeling.

If it is necessary to prevent the precipitation of salts in the pumping equipment, pipes and perforations 7, inhibitors (for example, diphonate) are added to the first 2-5% of the total volume of injected modified water. According to field experience, less than 2% of modified water with an inhibitor may not be enough to prevent premature salt deposition when replacing the withdrawn water with modified. While more than 5% leads to the absence of salt deposition in the bottomhole formation zone, and for the implementation of the isolation of the aquifer 2 it is necessary that salt deposition occurs in it.

The modified water injection operations are repeated with a new watering of the production well with water from aquifer 2 of at least 95%. According to calculations, when watering is more than 95%, it is difficult to re-isolate aquifer 2 with the least impact on oil reservoir 1, which can lead to loss of oil flow.

Injection well. Well 4 was drilled to inject wastewater into reservoir 1 for the purpose of maintaining reservoir pressure. Studies have shown that the bulk of the injected water goes into the aquifer 2 (for example, the lower one) due to the violation of the casing 5 and / or section 8 with the absence of cement stone 6.

All operations for the injection of modified water are carried out similarly to those described above in the production well. The operation of injecting modified water into the injection well is repeated with increasing injectivity to a value greater than the maximum injectivity of the productive oil reservoir 1.

The development is carried out until the full economically viable development of the deposit area.

The result of the implementation of this method is to increase the efficiency of elimination of annular circulation in production and injection wells and increase the duration of the effect.

Examples of specific performance of the method.

Example 1. The reservoir site is represented by two layers: oil saturated 1 with a thickness of 4 m and water saturated 2 with a thickness of 6 m, separated by a non-reservoir layer 3 of 2 m thick (Fig. 1). These reservoirs are opened by producing well 4.

The oil-saturated reservoir of the 1st section of the reservoir lies at an average depth of 1610 m, the initial reservoir pressure is 15.8 MPa, the gas saturation pressure of gas is 6.1 MPa, reservoir temperature is 30 ° C, the viscosity of the oil in reservoir conditions is 13.8 MPa · s, the permeability of the reservoir varies over a wide range - 50-650 mD, the total mineralization of produced water is 230.7 g / l, of which 192.4 g / l falls on NaCl salts, 8.2 g / l - MgCl 2 , 4.3 g / l - MgSO 4 , 25.5 g / l - CaCl 2 , 0.3 g / l - NaHCO 3 , the density of produced water - 1150 kg / m 3 .

The permeability of water-saturated formation 2 is 200-1900 mD, reservoir temperature is 30 ° C, the total mineralization of formation water is 245.5 g / l, of which 198.8 g / l are NaCl salts, 8.9 g / l - MgCl 2 , 4.9 g / l - MgSO 4 , 32.5 g / l - CaCl 2 , 0.4 g / l - NaHCO 3 , formation water density - 1165 kg / m 3 , maximum injectivity 200 m 3 / day.

The oil production rate of well 4 is 0.4 tons / day, liquid - 48.8 tons / day, water cut - 99.2%. The current reservoir pressure in the selection zone is 12 MPa. The influx of water is caused by the destruction of the cement stone 6 in the area 8 of the production casing 5. As a result, water from the aquifer 2 enters the perforations 7.

Preliminarily, laboratory tests are carried out at a reservoir temperature of 30 ° C on a core of an aquifer 2 for incompatibility between the reservoir and the modified water intended for water injection. For this, the extracted and evacuated core is saturated with a reservoir water model of formation 2 according to a known salt composition. After that, this core is flooded with various modified water. The concentration of salts in the modified water is determined, when mixed with produced water, salts precipitate and the permeability of the aquifer collector 2 decreases by a factor of 10 when pumping one core pore volume.

As a result of the studies, it was determined that water from the overlying carbonate formations is suitable as such modified water. The total salinity of the modified water is 192.3 g / l, of which 109.6 g / l are NaCl salts, 8.2 g / l - MgCl 2 , 2.1 g / l - MgSO 4 , 60.3 g / l - CaCl 2 , 12.1 g / l - NaHCO 3 . The density of produced water is 1132 kg / m 3 . A large number of salts of NaHCO 3 leads to a reaction in the reservoir conditions when mixing the reservoir and modified water:

CaCl 2 + 2NaHCO 3 ↔CaCO 3 ↓ + 2NaCl + H 2 O + CO 2 ↑.

In the course of laboratory studies, it is also determined that at a temperature of 60 ° C or more, the mixing of formation water of formation 2 and modified does not lead to the precipitation of salts, i.e. the specified reaction does not occur. Calculations on a 3D hydrodynamic thermal model with an adsorption option (for example, similar polymer flooding) show that at a temperature of injected water of 100 ° C, a flow rate of 200 m 3 / day (equal to the maximum injectivity) and a total injection volume of 6 · 300 = 1800 m 3 , water will sufficiently penetrate into the aquifer 2 and reduce the permeability to a level at which, after the well is launched into production, the main part of the inflow will come from the oil reservoir 1. At the same time, the oil reservoir 1 will almost not suffer from the action of the modified water.

Then, modified water is pumped, heated to a temperature of 100 ° C at the bottom through heat-insulated pipes to minimize heat loss to the external environment with a flow rate of 200 m 3 / day with a total volume of 1800 m 3 for 9 days.

Well 4 is put into production. The oil production rate of well 4 after taking part of the injected modified water was 7.2 tons / day, liquid - 22.6 tons / day, water cut - 68.3%. The duration of the effect was 1 year.

Modified water injection operations are repeated with a new watering of the producing well with water from an aquifer of 2 to 95%. The development is carried out until the full economically viable development of the deposit area.

According to the prototype, ceteris paribus, after the injection of the waterproofing composition, the oil production rate for well 4 was 4.7 tons / day, liquid - 28.1 tons / day, water cut - 83.4%. The duration of the effect was 3 months. The reduction in water cut according to the proposed method is 15.1% higher, and the duration of the effect is 4 times compared with the prototype.

Example 2. Perform as example 1. The formations have slightly different characteristics, the permeability of the reservoir is lower, the thickness of the water-saturated horizon 2 is 10 m, and its maximum throttle response is 100 m 3 / day. Modified water is pumped, heated to a temperature of 40 ° C at the bottom with a flow rate of 0.5 · 100 = 50 m 3 / day with a total volume of 20 · 10 = 200 m 3 for 4 days. In the first 2% of the total volume of injected modified water, i.e. 200 · 0.02 = 4 m 3 difonat added inhibitor.

Example 3. Perform as example 1. Well 4 is drilled to inject wastewater into reservoir 1 for the purpose of maintaining reservoir pressure, the current injection rate is 180 m 3 / day. In this case, the maximum injectivity of the oil-bearing horizon is 1-100 m 3 / day. Studies show that the bulk of the injected water goes to the lower aquifer 2 due to the lack of cement stone 6 in section 8. The modified water is injected as in example 1. In the first 5% of the total volume of injected modified water, i.e. 1800 · 0.05 = 90 m 3 add a diphonate inhibitor. Next, the well 4 is allowed to inject wastewater. The pick-up was 80 m 3 / day, the duration of the effect was 1 year. The operations for the injection of modified water into the injection well were repeated with increasing injectivity to a value greater than the maximum injectivity of the productive oil reservoir 1, i.e. more than 100 m 3 / day.

According to the prototype, ceteris paribus, after injection of the waterproofing composition, the injectivity of well 4 was 130 m 3 / day, the effect lasted 3 months. The proposed method allowed more efficiently to eliminate the absorption in the aquifer 2, and the duration of the effect was 4 times higher compared to the prototype.

Thus, the proposed method provides the elimination of annular circulation.

The application of the proposed method will solve the problem of increasing the efficiency of elimination of annular circulation in production and injection wells and increasing the duration of the effect.

Claims (1)

  1. A method for eliminating annular circulation, including selecting a producing or injection well with inflow or absorption into the higher or lower aquifers relative to the operating oil-bearing formation, shutting down the well, injecting composition to limit water inflow or water absorption, putting the well into operation, characterized in that Modified water is used as a composition for limiting water inflow or water absorption - water, the concentration and ionic composition of dissolved salts of which are determined by repeated studies of the decrease in core permeability of an aquifer not less than 10 times during the pumping of one pore volume of a core at reservoir temperature, while the decrease in permeability is the result of salt precipitation during the reaction of modified water with produced water of the aquifer, and modified water is heated to a temperature 40-100 ° С at the bottom and with a flow rate of 0.5-1.0 of the maximum injectivity of the aquifer, the total injection volume is determined as 20-300 m 3 per 1 m of the effective thickness of the aquifer In the first 2-5% of the total volume of injected modified water, inhibitors are added, if necessary, to prevent the precipitation of salts in the pumping equipment and pipes, the operations for injecting modified water are repeated when the production well is irrigated with water from the aquifer to at least 95% or while increasing the injectivity of the injection well to a value greater than the maximum injectivity of the productive oil reservoir.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727687A (en) * 1971-07-01 1973-04-17 Phillips Petroleum Co Aqueous gels and uses thereof
SU681993A1 (en) * 1978-05-04 1991-12-23 Татарский государственный научно-исследовательский и проектный институт нефти Oilfield development process
RU2271445C1 (en) * 2004-12-22 2006-03-10 Геннадий Иванович Суворов Method for well remedial cementing
RU2361062C1 (en) * 2007-11-02 2009-07-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Method of elimination of behind-casing flow in wells of small diametre
RU2413840C1 (en) * 2010-05-06 2011-03-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Procedure for elimination of cross-feeds
RU2527053C1 (en) * 2013-10-04 2014-08-27 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Development method of fractured-porous types of reservoirs
RU2547868C1 (en) * 2013-12-05 2015-04-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный минерально-сырьевой университет "Горный" Method of development of oil pool with argilliferous reservoir

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727687A (en) * 1971-07-01 1973-04-17 Phillips Petroleum Co Aqueous gels and uses thereof
SU681993A1 (en) * 1978-05-04 1991-12-23 Татарский государственный научно-исследовательский и проектный институт нефти Oilfield development process
RU2271445C1 (en) * 2004-12-22 2006-03-10 Геннадий Иванович Суворов Method for well remedial cementing
RU2361062C1 (en) * 2007-11-02 2009-07-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Method of elimination of behind-casing flow in wells of small diametre
RU2413840C1 (en) * 2010-05-06 2011-03-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Procedure for elimination of cross-feeds
RU2527053C1 (en) * 2013-10-04 2014-08-27 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Development method of fractured-porous types of reservoirs
RU2547868C1 (en) * 2013-12-05 2015-04-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный минерально-сырьевой университет "Горный" Method of development of oil pool with argilliferous reservoir

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