Method of development of heterogeneous-layer oil deposits. RU patent 2508446.

FIELD: oil-and-gas industry.

SUBSTANCE: proposed method comprises injection of working agent via injection wells, extraction of oil via production wells, injection of sealing agent based on sodium silicate and acid into injection or production wells, holding the welds for a day and making them operate. Prior to injecting said sealing agent into bed, water-slug is injected in amount inhibiting the mixing of bed water with sealing agent till its gelation but not smaller than one volume of tubing. Holding is performed after injection of said agent into the bed. Sealing agent is composed by gel-like compound of the following composition, wt %: sodium silicate - 3-8, sulfonic acid - 0.38-1.5, chromium acetate - 0.35-0.9, monoethanol-amine - 0.35-0.9.

EFFECT: higher efficiency of sealing.

2 ex, 1 dwg

The invention relates to the oil and gas industry, in particular to methods of oil production from inhomogeneous watered formations at the late stage of development of oil fields.

There is a method of selective isolation of water inflow into the oil wells, providing for the pumping of water soluble acrylic series [kleschenko I.I., A.V. Grigoriev, A.P. Insulation work during completion and operation of wells. - M Nedra, p.31]. Isolation mechanism of formation waters based on the interaction of acrylic polymers with salts formation waters or adsorption of polymers on the breed. However, this method is applicable only if the isolation of formation of highly mineralized water chlorine-calcium type.

There is a method of limitation of water flow into the well, including sequential injection of an aqueous solution of sodium silicate and hardener - [SU, №1423726, 21 33/12, 1988]. The aqueous solution of sodium silicate reacts with the hardener - solution of hydrochloric acid, as a result of which produces high-viscosity gel, which then turns the substance - , pores.

The disadvantages of this method is, that in the process of injection is prematurely and uneven mixture injected solutions, with the formation of blocking the screen near the discharge line, and even in the well bore. In the result, the composition does not reach the destination and not achieved wide coverage of the flooded areas of the reservoir.

The closest analogue of the invention is a way to develop a layered inhomogeneous oil fields (Russia, №2128768, 21 43/22, 1999), applied at processing of bottom-hole zones extractive or injection wells to water influx isolation in production wells and alignment of injectivity of wells, as well as with isolation of cross-flows in wells and the liquidation of old wells. By way inject the insulating agent through injection wells, select oil through production wells. In flooding of production wells wells pumped insulating agent on the basis of silicate of sodium and hydrochloric acid. Well kept for the day and start in work.

The disadvantage of a low efficiency of insulation, short time of gelling, low strength (30) and the risk of precipitation of salts of silicic acid at a meeting gel-forming composition with highly mineralized stratal waters.

In the invention solved the technical problem of improving the efficiency of isolation due to the increased time of gelling, increase the strength of the gel.

The task is solved by a how to develop layered inhomogeneous oil fields, including the injection of the agent through injection wells, selection of oil through production wells, injection, injection or producing wells in flooding wells isolation agent on the basis of silicate of sodium and acid, extract of wells during the day and run them in the work, according to the invention before the injection isolation agent into the reservoir, pump fresh water in a volume that provides produced water with insulating agent before the time of his , but not less than one volume of tubing, the shutter speed is carried out after the agent in the formation, and as an isolation agent use composition in the following composition, mass%:

Sodium silicate

Sulfamic acid

Chromium acetate

Monoethanolamine

Thus, the proposed method differs from analogue novelty composition and method of injection of the composition to the formation. The additional introduction of chromium acetate acid-gel-forming system (sodium silicate + sulfamic acid) leads to further strengthening of the system. This happens due to the formation of complexes between negatively charged silicate ions and cation of chromium in three dimensions. Thus gel is formed by hydrogen bonds with silicic acid, strengthens spatial silicate complexes.

In addition, the difference between a prototype and a novelty of the method is the method of injection, which consists in preliminary downloading of the reservoir rim of fresh water to push mineralized stratal waters to prevent precipitation of the reaction of metal salts with silicate ions according to the scheme:

Na 2 Si 3 O 7 +CaCl 2 =CaSi 3 O 7 |+2NaCl

Na 2 Si 3 O 7 +MgCl 2 =MgSi 3 O 7 |+2NaCl

Volume rim of fresh water are selected so that the while pushing through the layer of insulating agent, due to the formation of «languages», and the composition is not mingling would mineralized formation water up to the end of the term of gelation. For this volume rim of fresh water are at least one volume of tubing, the higher the volume, the better the resulting insulating effect.

To determine the optimal ratio of reagents, experiments were conducted with different proportions of components.

Used sodium silicate powder, dried in a spray drier plant OJSC tanning agent» with the module 2,95. Sulfamic acid (NAO) was used 15%concentration density 1,083 g/cm 3

Chromium acetate (AX) used in the form of 10%solution with density 1,039 g/cm 3 .

Monoethanolamine (MEA) used in the commodity undiluted form.

Mainly studies were conducted with isolating agents, containing in its composition 5-7% sodium silicate, which is obtained sufficient strength gel (1000-7000 PA) at the required time (10-20 hours).

The results of the laboratory work graphs of the time dependence of the beginning of gel formation and strength of the received gel from sulfamic acid concentration (BAC) of figure 1.

As can be seen, with increasing content of the sulfamic acid in the solution, the strength of the isolation of the agent increases, and the start time of gelling decreases, therefore, to obtain a sufficiently strong gels with required time of gelling you must choose the optimum concentration of sulfamic acid, that is from 0.8% to 1.6% of the mass.

When the content of SAK more than 1.6% of the mass. dramatically reduces the time of gelling, although the strength is high. In reducing the number of SAK less than 0.8 gel formation is slow, but reduced strength characteristics.

As can be seen from the figure, compared with the prototype of the proposed composition of the gelation time is increased to 2.28 times, and strength increases in 230 times.

Thus, the goal of the project of the claimed invention is considered to be solved.

Example of the implementation of the proposed method on the producer. Well depth of 3500 meters, tubing launched 3250 m, the thickness of the productive formation of 2,5 m

Preparing to 25 m 3 of water isolation agent with the following composition: 6,4% sodium silicate, 0.7% of chromium acetate, 1,064% SAK, 2.5% of the IEA and 89, 366% water.

Originally tubing is served 25 m3 of fresh water. Following the fresh water is pumped 25 m 3 of water isolation agent (2,5 volume of tubing). Then in the tubing is served 10 m 3 fluid (which applies fresh water) and the previous volume of liquids is squeezed into the formation. Well the day is left to the solidification of the gel, then proceed to the process of development.

Example of the implementation of the proposed method on the discharge hole. Well depth of 3000 m, pipe discharge lowered to 2900 m, capacity of the receiving reservoir 1,5 m

Preparing 15 m 3 of water isolation agent containing 6,7% of the mass. sodium silicate, 0,82% of the mass. chromium acetate, 0.85% of sulfamic acid and 1.50% monoethanolamine and 90,13% water.

In the injection pipe originally served 20 m 3 rim of fresh water (two volumes of pipes, then pumped 15 m 3 of water isolation agent. The whole mixture is squeezed into the formation liquid (fresh water) in the amount of injection pipe 10 m 3 . Well it is left on 24 hours for «seizure», then resumed the work on discharge of water.

Application of the proposed method allows to successfully develop heterogeneous permeability, flooded deposits with simultaneous increase of the oil recovery ratio and reduce the water content of products.

Way to develop a layered inhomogeneous oil fields, including the injection of the agent through injection wells, selection of oil through production wells, injection, injection or producing wells in flooding wells isolation agent on the basis of silicate of sodium and acid, extract of wells during the day and putting them into operation, wherein the previously, before the injection isolation agent into the reservoir, pump fresh water in a volume that provides produced water with insulating agent before the time of his , but not less than the volume of tubing, the shutter speed is carried out after the agent in the reservoir, and as an isolation agent use composition of the following composition,% Mas.:

Sodium silicate

Sulfamic acid

Chromium acetate

Monoethanolamine