RU2043494C1 - Method for development of water-encroached nonuniform formation of oil pool - Google Patents

Abstract

FIELD: development of oil pools. SUBSTANCE: method for development of water-encroached nonuniform formation of oil pool includes injection into formation of aqueous suspension of wood flour in the amount of 50-300 cu.m per meter of operating thickness of formation. EFFECT: higher efficiency of development of water-encroached nonuniform oil formation. 1 tbl

Description

 The invention relates to the oil industry, in particular to methods for developing a heterogeneous reservoir of oil deposits by flooding.

 A known method of developing a heterogeneous oil reservoir by pumping into an area of water washed with an aqueous suspension of bentonite clay with subsequent flooding [1] The disadvantage of this method is its low efficiency in fractured-pore-cavernous reservoirs.

A known method of developing a heterogeneous oil reservoir by injection into a flooded reservoir of cationic and anionic polyacrylamide, followed by displacement. The disadvantage of this method is its low efficiency in fractured-pore-cavernous reservoirs and the inability to use it in reservoirs with a temperature of more than 90 ^about C.

The closest in technical essence and the achieved result to the claimed method is a method of developing a heterogeneous reservoir of oil deposits, including flooding, sequentially alternating injection into the flooded reservoir of an aqueous solution of partially hydrolyzed polyacrylamide and clay slurry and subsequent injection of the displacing agent [2]
The disadvantage of this method is the low efficiency of the process in fractured porous cavernous reservoirs due to the low isolation of selectivity due to the fact that along with the insulated high-permeability of the reservoir, a partial blockage of the low permeable portions of the formation and the impossibility of its use in reservoirs with temperatures over ⁹⁰ C. The present invention is based on the task of creating a method for developing a heterogeneous reservoir of oil deposits, including the injection of an aqueous suspension of wood flour.

 A new set of claimed essential features allows to obtain a new technical result, namely, to increase the efficiency of developing a heterogeneous oil reservoir by increasing the selectivity of isolation of highly permeable sections of the reservoir while simplifying the process and reducing the injection time.

 An analysis of the well-known solutions selected during the search showed that there is no object in science and technology that is similar to the claimed combination of essential features and has high rates in the development of a heterogeneous oil reservoir.

 Wood flour, unlike clay particles, is large (70-160 microns versus 10-25 microns) and, after injection, a suspension of wood flour penetrates and isolates only high-permeability sections of the formation, without penetrating or clogging low-permeability sections of the formation.

 Wood flour (GOST 16361-87) is a product of dry grinding of waste from the woodworking industry (sawdust, wood chips, lumpy wood waste, etc.). Wood flour is delivered to the place of use in dry form, packaged in paper bags, and it is pumped into the formation by pouring it into the water conduit through the loading chamber of the ejection pump.

 To prove the compliance of the claimed invention with the criterion of "industrial applicability" we give specific examples of the method.

где Q_в расход жидкости по высокопроницаемому пропластку, м³/сут;
h_в толщина высокопроницаемого пропластка, м;
Q_н расход жидкости по низкопроницаемому пропластку, м³/сут;
h_н толщина низкопроницаемого пропластка, м.Evaluation of the effectiveness of the proposed method and the prototype method is performed by the dimensionless coefficient of heterogeneity of filtration
K

where Q _{is the} fluid flow rate for a highly permeable interlayer, m ³ / day;
h _{in the} thickness of the highly permeable layer, m;
Q _n fluid flow rate for low permeability interlayers, m ³ / day;
h _{n the} thickness of the low permeability layer, m

The technology for pilot works consists in pumping 0.1-5.0% suspension of wood flour into the injection wells of the flooded formation. Next, a displacing agent is injected. As the object of testing, a formation was presented, represented by a fractured-pore-cavernous reservoir with different permeable layers. The permeability of the low permeability layer is 0.01-0.08 μm ² , high permeability 0.2-1.4 μm ² . The water content of the extracted products is 90-98% reservoir temperature of 90 ^about C.

 PRI me R 1 (known method).

 A complex of geophysical and hydrodynamic studies is carried out at the well, low-permeable and high-permeability layers and their relative injectivity are determined. The amount of injected reagents is calculated. A 0.04% aqueous solution of partially hydrolyzed polyarylamide and a 5% clay slurry are pumped into the flooded formation using a pumping unit of the type CA-320m in a sequentially alternating mode in 4 cycles. Next, a displacing agent, for example water, is pumped.

 The degree of change in the heterogeneity of the filtration is negligible (table. Example 1).

PRI me R 2. Preparation of a well for injection is carried out analogously to example 1. Then, a 5% aqueous suspension of wood flour in the amount of 150 m ³ per 1 m of effective thickness of the layer is pumped into the flooded formation using a pumping unit of the type CA-320M. Next, the displacing agent is pumped. Due to a sharp increase in the heterogeneity of the filtration (89.0%), the flow of water into the low-permeability layers significantly increases (Table. Example 2).

The table below provides examples of the effectiveness of the method with a concentration of wood flour of 0.1% and 1.5% in an amount of 50 m ³ and 300 m ³ per 1 m of effective formation thickness (table. Examples 3.4). When wood flour is injected less than 50 m ³ per 1 m of effective formation thickness, the effect of isolating a highly permeable layer is not achieved, when using wood flour in an amount of more than 300 m ^{3, the} development of the method becomes economically impractical due to a significant increase in the processing time of one well.

The proposed method in comparison with the known has several advantages:
the efficiency of the method is increased by increasing the selectivity of isolation of highly permeable layers from 36% to 76.3-89.0%
expanding field of application because of the possibility of using the method in reservoirs with temperatures greater than 90 ^{° C;}
a non-deficient chemical is used;
cheaper technology;
the method is implemented using standard techniques;
through the use of natural material of plant origin, the development does not have a harmful effect on the ecological situation in the area of use.

Claims (1)

METHOD FOR DEVELOPING AN IRRIGATED INHOMOGENEOUS OIL DEPOSIT LAYER, including the injection of an aqueous suspension of dispersed particles, characterized in that wood flour is used as dispersed particles, and the aqueous suspension is pumped in an amount of 50 300 m ³ per 1 m of working thickness of the formation.

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