RU2431747C1 - Procedure for development of multi-pay oil deposit - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: procedure for development of multi-pay oil deposit consists in casing string opening, in lowering packer on oil-well tubing (OWT), in positioning packer between reservoirs, in pumping hardening back-filling solution and in its conditioning. Back-filling solution is preliminary pumped and pressurised into a lower watered reservoir. Upon back-filling solution hardening in the reservoir the casing string is opened above the lower reservoir. Packer is set above interval of casing string perforation. A connecting rod receiving fluid from the watered reservoir by means of the pump is arranged at a lower end of the OWT string.

EFFECT: raised efficiency of procedure for development of multi-pay oil deposit due to maintaining operational mode of producer and elimination of filtration of reservoir water through annular space to upper payout reservoir of well thus increasing well operation period; reduced well production watering and increased reservoir recovery.

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Description

The proposed method relates to the oil industry, in particular to methods for developing a multilayer oil reservoir and limiting water inflow in a producing well that has uncovered two or more productive formations.

There is a method of isolating the casing leakage interval in the well (patent RU No. 2254443, E21B 33/13, publ. Bull. No. 17 dated 06/20/2005), which includes determining the casing leakage interval, the formation of a screen from a viscoplastic mass in the annulus by injection into well and pushing into its annular space under excess pressure of the working fluid for its interaction with the developing fluid. The well is maintained at excess pressure until a set of viscoplastic mass of at least 30% of the final planned structural strength is set. Then the residues of the viscoplastic mass are removed from the casing at overpressure, excluding the backflow of the main volume of the viscoplastic mass from the annulus to the casing, after which the well is kept until the viscoplastic mass reaches the final structural strength.

The disadvantage of this method is the low efficiency due to the fact that the insulating material penetrates primarily into the highly permeable channels of the formation and to a shallow depth, leaving shallow pores and cracks with higher filtration resistance uninsulated, which reduces the tightness of the casing in the well and, as consequence, leads to the rapid restoration of annular flows.

The closest in technical essence to the proposed is a method of repairing a well, including opening a casing string, running a packer on the nasal tubing (tubing), installing a packer between the strata, pumping the grouting solution into the annulus, waiting for it to solidify, and removing the packer (RU patent No. 2354802, E21B 29/10, 33/13, publ. Bull. No. 13 of 05/10/2009). Before the injection of insulating material, the under-packer space is filled with insulating material and the packer is placed. The installation of the packer is performed between the lower and upper reservoirs. To pump insulating material into the annulus, increase the pressure in the under-packer space, reduce the pressure in the well in the over-packer space without reducing the pressure in the under-packer space. Before removing the packer, the pressures in the above-packer and under-packer spaces are equalized, after removing the packer, the well is washed from the remnants of the insulating material and technological exposure is carried out to set and harden the insulating material.

The disadvantage of this method is that the known method does not allow to exclude the filtration of formation water through the annulus to the upper productive formation of the well, which, in turn, prevents the flow of oil to the perforation intervals and increases the water cut of the well production. In cases where the lower layer is highly receptive, then all injected solutions clog it, and not annular flows.

The technical task of the proposed method is to increase the efficiency of the method of developing a multilayer oil reservoir by maintaining the operational mode of operation of the producing well and eliminating the filtration of formation water through the annulus to the upper producing formation of the well, reducing the water cut of the production of the well and increasing oil recovery.

This problem is solved by the method of developing a multilayer oil reservoir, including opening the casing string, lowering the packer on the nasal tubing (tubing), installing the packer between the strata, injecting the hardening grouting mortar and waiting for it to solidify.

New is that the cement slurry is pre-pumped and pushed into the lower waterlogged formation, after the cement slurry is cured, the casing is opened above the lower formation, the packer is installed above the casing perforation interval, and a fitting is installed at the bottom of the tubing string for pumping fluid from a watered formation.

The drawing shows a section of an oil-saturated formation with a vertical well placed by the proposed method.

SUMMARY OF THE INVENTION

The oil reservoir is drilled with wells 1 according to the design grid, their arrangement is carried out, the geological structure of the reservoir is determined, the reservoir properties of the reservoirs are determined: upper 2 and lower 3, the thickness of clay rocks 4 separating the upper reservoir 2 from the lower 3. In production well 1, produce perforation of the 5 casing string and selection of well production from the productive formations 2 and 3. Produce regularly measured oil and water. The water cut of layers 2 and 3 is determined by their production in the well, the reasons for its growth are identified. During operation, the water cut of the lower highly-productive reservoir increases. If the integrity of the annular space is violated, annular flows occur and flooding of the upper productive layer occurs. Oil production is reduced to unprofitable.

In order to maintain the operating mode of the production well and to exclude the formation water filtration through the annulus to the upper producing formation, reducing the water cut of the production of the well and increasing oil recovery, isolating the lower highly sensitive producing formation 3, grouting mortar 6 is pumped into it. As a grouting grout, use for example, a gel-forming composition, etc. The amount of cement slurry needed to damp out a waterlogged formation depends on the thickness of the reservoir and its permeability.

After the cement slurry 6 is cured in the lower layer 3 above the lower layer, in the interval of low-cemented clay rocks, the well casing 1 is opened with perforation 7. The perforation interval 7 is one to two meters above the roof of the lower layer 3. Lower the packer 8 onto the nasal compressor pipes (tubing) 9 and is installed between the upper 2 and lower layers 3 above the perforation interval 7. In the annular space 10 injected hardening cement slurry (for example, gelling compositions, etc.). The well is stopped for technological exposure, depending on the composition of the cement slurry. As grouting compositions, cement mortars, aqueous polymer solutions, etc. are used. After injection of the cement slurry, a gel-forming composition is pressed to fill the annular space.

A fitting 11 is installed in the bottom of the tubing string 11. The bottom of the tubing string is placed above the roof of the lower formation 3 at a distance of 1.0-1.5 m. When the pressure in the subpacker zone is higher than the pressure in the overpacker zone, formation fluid flows through the nozzle from bottom to top in nadpakarny zone from which it is selected by the deep-pumping equipment.

Due to the creation of depression in the bottom-hole zone, the proposed method provides a smooth establishment of the required operational mode of operation of the well and eliminates the filtration of formation water through the annulus to the upper productive formation of the well, which, in turn, prevents the flow of oil to the perforation intervals and increases the water cut of the well production.

The method ensures the preservation of the permeability of the oil-saturated part of the reservoir, reduces the water cut of the product by more than 15% by eliminating the permeability between the reservoirs in the annulus of the well, eliminates the flow of water from the lower flooded reservoir into the upper reservoir, which contributes to an increase in oil production and, accordingly, oil recovery.

Concrete example

The oil reservoir is drilled with wells according to the design grid, and their arrangement is carried out. Production well 1 opened two productive formations 2 and 3. The thickness of weakly cemented clay rocks 4 separating the formations is eight meters.

In the producing well, productive formations 2 and 3 are opened by perforation 5. During operation, the selected oil and water are regularly measured. The water cut of layers 2 and 3 is determined by their production in well 1, the reasons for its growth are identified. After a year of well operation, the lower layer 3 was watered. As a result, the water cut of extracted products increased to 92%. Oil production from the upper layer 2 decreased from 9.2 tons / day to 0.8 tons / day. Based on the data obtained, the presence of annular flows of formation water between formations 2 and 3 is established. Formation water from the lower formation 3, rising up the annular space, prevents the flow of oil from formation 2 to the perforation intervals.

In order to isolate the lower layer 3, an aqueous solution of polymers 6 is pumped into it in an amount necessary to kill the formation.

After the cement slurry 6 is cured in the lower layer 3 above it, in the interval of low-cemented clay rocks, the well casing 1 is opened with perforation 7. The perforation interval 7 is two meters above the roof of the lower layer 3. After the tubing is lowered, the packer 8 is installed between the upper layer 2 and a perforation interval 7 at a distance of 1.5 m above the perforation interval. In the annular space 10 is injected hardening cement slurry - an aqueous solution of polymers. The well is stopped for technological exposure, depending on the composition of the cement slurry.

A fitting 11 is installed in the lower part of the tubing string. The lower part of the tubing string is placed above the roof of the lower layer 3 at a distance of 1.5 m.

The proposed method allows to increase the efficiency of the method of developing a multilayer oil reservoir by maintaining the operational mode of operation of the producing well and eliminating the filtration of produced water through the annulus to the upper producing formation of the well, thereby extending the period of operation of the well, reducing the water cut of the production of the well and increasing oil recovery.

Claims (1)

A method of developing a multilayer oil reservoir, including opening a casing string, running a packer on the nasal compressor tubes (tubing), installing a packer between the strata, injecting the hardening grouting mortar and waiting for it to solidify, characterized in that the grouting mortar is pre-pumped and forced into the lower flooded reservoir , after curing the grout in the formation, the casing is opened above the lower layer, the packer is installed above the perforation interval of the casing, and on the lower the end of the tubing string set the fitting for fluid intake by the pump from the watered formation.

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