RU2527949C1 - Procedure for development of oil deposit with clayey collector - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method involves pumping of working agent through injectors and recovery of products through producers. For the purpose of development a pool or a poll part is selected with formation pressure at least equal to the initial one, water cut of 60% and more and recoverable reserves of at least 40 thousand t. Then the post-event analysis is made for the selected section in regard to changes in dynamics of formation and bottomhole pressure and the least worked-out section with content of clay fraction of 2.5% and more. Upon the preformed analysis several design point of drilling for vertical inclined well are replaced by one injector with horizontal completion. The horizontal shaft is placed in the stratum with thickness of at least 3 m. The shaft is constructed at the border of the reservoir collector transition from clayey sandstone to aleurolite. Upon input of the horizontal injector into operation liquid is injected into the stratum under permanent control of changes in operation mode of the surrounding producers by means of bottomhole pressure measurement and product water cut. When bottomhole pressure rises up to the value sufficient to intensify product recovery operations on optimisation of subsurface pumping equipment are made to a bigger standard size. Upon the preformed analysis several design point of drilling for vertical inclined well are replaced by one producer with horizontal completion. The horizontal shaft is placed in the stratum with thickness of at least 3 m. The shaft is constructed at the border of the reservoir collector transition from clayey sandstone to aleurolite. Upon input of the horizontal producer into recover of reservoir liquid is made under permanent control of changes in operation mode of the surrounding producers by means of bottomhole pressure measurement and product water cut. When bottomhole pressure decreases per 10% below saturation pressure operations on injection increase are made through the affecting injectors.

EFFECT: improving oil recovery in the deposit with clayey collector.

2 cl, 2 ex

Description

The invention relates to the field of oil field development and can be used in the development of an oil field with clay reservoirs.

A known method of developing a zone-heterogeneous oil field, including drilling production and injection wells, cyclic injection of water and periodic selection of production through production wells, closing the production well when the water cut is reached, injecting the rim of the surfactant surfactant solution into the injection well, pushing it along to the reservoir with water, the producing well located in the clay reservoir is closed when the water cut of the reservoir reaches 50-99%, into the injection well Inu is injected with a polymer rim and pushed through the formation with water, then the production wells that are in mutual influence are closed and the production well is opened in the clay reservoir, the rim of the surfactant solution is pushed into the injection well with highly mineralized formation water, after which the wells that are in the mutual influence are opened and selection is performed products from all production wells during cyclic injection of highly saline water. Crosslinked polymer systems can be used as a polymer, and compositions based on nonionic and anionic substances can be used as surfactants (RF Patent No. 2206727, publ. 06/20/2003).

Closest to the proposed invention in technical essence is a method of developing an irrigated zone-heterogeneous oil field, which includes opening at least one injection and several production wells. Rims of the agent increasing the filtration resistance of the porous medium and water are pumped into the injection well. Change the operating mode of production and injection wells during the injection of reagents. At the same time, a production well located in a clay reservoir is shut off. A rim of the agent increasing the filtration resistance of the porous medium and a portion of the rim of the stabilizing composition are sequentially pumped into the injection well. Then, the injection well is turned off and a time delay is sufficient to redistribute the filtration flows. After that, the production well located in the clay reservoir, and the injection open. A second portion of the stabilizing composition is pumped. Then they switch to normal flooding. The injection pressure in the injection well is maintained constant, corresponding to the pressure of the selection of products from production wells (RF Patent No. 2208139, publ. 07/10/2003 - prototype).

A common drawback of the known technical solutions is the development without taking into account the radius of supply of the producing well or the influence of the injection well in a clay reservoir, which leads to a low degree of oil recovery from the reservoir.

The proposed invention solves the problem of increasing oil recovery of oil deposits with a clay reservoir.

The problem is solved in that in the method of developing an oil reservoir with a clay reservoir, including pumping a working agent through injection wells and selecting reservoir products through production wells, according to the invention, a reservoir or a reservoir section with reservoir pressure not lower than the initial one with a water cut of 60% is selected for development and more, and with the presence of at least 40 thousand tons of recoverable reserves, then a retrospective analysis is carried out in this area for changes in the dynamics of reservoir and bottomhole pressures and the least A work area with a clay fraction content of 2.5% or more, after the analysis, several design points for drilling vertical injection wells are replaced with one injection well with a horizontal end, a horizontal well is placed in the formation with a strike power of at least 3 m, and the well is drilled on the border of the transition of the reservoir rock from clayey sandstone to siltstone, after putting into operation a horizontal injection well, fluid is injected into the reservoir with a constant m shift control in operation surrounding producing wells by means of measurements downhole pressure and water cut, after receiving growth bhp, sufficient for enhanced product selection, produce work to optimize downhole pumping equipment to a larger size.

After the analysis, several design points for drilling vertical production wells are replaced with one production well with a horizontal end, a horizontal well is placed in the formation with a strike force of at least 3 m, the well is drilled at the boundary of the transition of the reservoir rock from clayey sandstone to siltstone, and after input a horizontal production well is taken into operation from the reservoir with constant monitoring of changes in the operating mode of the surrounding production wells by measuring bottomhole pressure and water cut, after receiving a bottomhole pressure decrease of 10% below the saturation pressure, work is underway to increase injection through impacting wells.

SUMMARY OF THE INVENTION

With the development of residual reserves and an increase in the share of clay reservoir reserves, the question arises more and more about increasing the extraction area of one well from the entire development site, i.e. it is necessary to create such a supply radius for the producing well or the influence of the injection well so that it is possible to produce additional reserves of the development site using newly drilled wells and wells with an increased supply radius. Existing development methods do not solve this problem. To increase the supply circuit to the producing well, it is proposed to drill the horizontal part of the wellbore along the reservoir, while using this technology implies the elimination of such risks as getting wedging zones and zonal heterogeneity. Using information on previously drilled wells and formations and based on the filtration and reservoir properties of the bottom-hole zones of neighboring wells, especially in terms of the presence of pinching of productive layers and the presence of a clay component, a design well is selected for drilling a horizontal well. Thus, having sufficient material for the presence of zones of heterogeneity and increased clay content, the least risky installation of the horizontal part of the wellbore along the selected formation is chosen, while the direction of drilling of the horizontal part of the wellbore provides an increase in the filtration zone of the inflow to the producing well. When planning the drilling of the horizontal part of the injection well bore, in addition to the previously described well selection criteria, a criterion such as a reduced reservoir pressure from neighboring production wells from the original to ~ 10/12 MPa also appears. Thus, when drilling a section of a deposit at a late stage of development, the issue of increasing oil recovery in the case of a producing well is being resolved. there is a natural increase in the radius of supply in the case of a producing well, and an increase in coverage by displacement in the case of an injection well.

Case Studies

Example 1. For development, a reservoir is selected with the following characteristics: reservoir pressure 10 MPa, reservoir temperature 32-38 ° C, oil-water contact depth 1600-2200 m, porosity 5-50%, permeability 5-1100 mDa, oil saturation 40-90%, oil viscosity 12-35 mPa * s, oil density 0.862-0.892 g / cm ³ , the reservoir is zone-heterogeneous, consists of clay sandstone zones with clay content from 2 to 7% and siltstone zones. The deposit has been developed for 10 years. The current water cut of stratum products ranges from 60 to 90%. The average production rate of production wells is 2-20 m ³ / day, the average injection rate of injection wells is 5-150 m ³ / day. Estimated recoverable reserves are 40 thousand tons of oil. Formation water is pumped through 5 injection wells and formation products are collected through 10 production wells.

A retrospective analysis of the change in the dynamics of reservoir and bottomhole pressures is carried out for the deposits. It is established that during the development process, a gradual decrease in reservoir pressure by 5-15% relative to the initial one is observed, which inevitably leads to a decrease in the volume of produced products, on the basis of which the least developed area of production and injection wells with a clay fraction of 2.5% or more is selected . After the analysis, substitution is made from 3 design points for drilling vertical injection wells with one injection well with a horizontal end with a horizontal wellbore length of 200 m and more. A horizontal wellbore is placed in the formation with a strike power of at least 3 m. The well is drilled at the boundary of the reservoir clay sandstone in siltstone. After commissioning a horizontal injection well, fluid is injected into the formation with constant monitoring of changes in the operating mode of the surrounding producing wells by measuring bottomhole pressure and water cut of the product. After obtaining a bottomhole pressure increase of 5%, sufficient to intensify the selection of products, work is carried out to optimize the downhole pumping equipment for a larger standard size.

Example 2. Perform, as example 1. On the other side of the selected least developed section of production and injection wells with a clay fraction of 2.5% or more, the replacement from 4 design points for drilling vertical production wells with one production well with a horizontal end with a horizontal length of 250 m of the trunk. A horizontal well is placed in the formation with a strike power of at least 3 m. The well is drilled at the boundary of the transition of the reservoir rock from clayey sandstone to siltstone. After commissioning a horizontal production well, fluid is taken from the reservoir with constant monitoring of changes in the operating mode of the surrounding production wells by measuring bottomhole pressure and water cut of the product. After receiving a bottomhole pressure decrease of 10% below the saturation pressure, work is carried out to increase injection in the impacting injection wells.

As a result of development, it is possible to achieve oil displacement from the zone of the reservoir with a clay reservoir, the oil recovery of the reservoir is increased by 2.5%.

The application of the proposed method will improve oil recovery deposits.

Claims (2)

1. A method of developing an oil reservoir with a clay reservoir, including pumping a working agent through injection wells and selecting reservoir products through production wells, characterized in that a reservoir or a reservoir section with reservoir pressure not lower than the initial one with a water cut of 60% or more is selected for development , and the presence of at least 40 thousand tons of recoverable reserves, then a retrospective analysis of the change in the dynamics of reservoir and bottomhole pressures is performed in this area and the least developed area with soda is selected the clay fraction is crushed from 2.5% or more, after the analysis, several design points for drilling vertical injection wells are replaced with one injection well with a horizontal end, a horizontal well is placed in the formation with a strike force of at least 3 m, the well is drilled at the transition boundary reservoir rocks from clay sandstone to siltstone, after putting into operation a horizontal injection well, fluid is injected into the formation with constant monitoring of change m in the operating mode of the surrounding production wells by measuring bottomhole pressure and water cut of the product, after receiving a bottomhole pressure increase sufficient to intensify the selection of products, work is carried out to optimize the downhole pumping equipment for a larger standard size. 2. The method according to claim 1, characterized in that after the analysis, several design points for drilling vertical production wells are replaced with one production well with a horizontal end, a horizontal well is placed in the formation with a strike force of at least 3 m, the well is wired at the boundary the transition of the reservoir rock from clay sandstone to siltstone, and after commissioning a horizontal production well, fluid is taken from the reservoir with constant monitoring of the change in the operating mode s surrounding production wells through measurement of bottomhole pressure and water production, after receiving reduce the bottomhole pressure by 10% below the saturation pressure produces work to increase the injection of influencing injection wells.