RU2425970C1 - Clay cake removal method of bottom-hole zone - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in clay cake removal method of bottom-hole zone, which involves pumping of clay cake removal material, process exposure and development of well, clay cake removal material is pumped in two margins with equal volumes; the first margin includes the following composition as clay cake removal material including the following, wt %: 0.1-2 surface active substance ML-81 B, 0.1-5 sodium hydroxide, 0.05-5 water-soluble polymer and water is the rest; and the second margin contains the compound as clay cake removal material including the following, wt %: 0.1-2 surface active substance ML-81B, 0.1-5 sodium hydroxide, and water is the rest.

EFFECT: increasing the action efficiency.

3 ex

Description

The invention relates to the oil industry and may find application in the claying of the bottomhole zone of a well.

A known method of processing oil and gas reservoirs, including the extraction of oil or gas from wells. After the appearance of water in the product, an intensifying agent is pumped through production or injection wells to wedge and increase the permeability of the formation. Then flux-diverting or water-insulating reagents are pumped, forming a screen-barrier on the path of water on the highly permeable zones of the reservoir. Before processing, according to the data of geophysical, hydrodynamic studies or the study of core material, colmated non-working productive intervals of the formation are determined. After the injection of flow-diverting or water-insulating reagents, ultrasonic processing of low-permeable and idle sealed reservoir intervals is carried out (RF patent No. 2208136, publ. 10.07.2003).

Closest to the proposed invention in technical essence is a method of developing an oil reservoir with a low-permeability clay-containing reservoir, which involves loosening production and injection wells, followed by oil displacement from the reservoir with a polymer solution. Claying is carried out with different values of the amount of decolming reagent, depending on the permeability of the bottom-hole zones of the wells being treated, the concentration of the aqueous polymer solution is selected in the range between the concentration at which the mobility of the aqueous polymer solution in the clayed-out bottom-hole formation zone is equal to the mobility of water in this zone before the claying, and the concentration, at which the specific increase in oil recovery deposits is maximum (RF patent No. 2105141, publ. 02.20.1998 prototype).

The disadvantage of this method is the low efficiency of the claying process due to the fact that the processing of the claying composition is mainly carried out at high permeability intervals of the formation, while low permeability layers remain unaffected. This leads to the fact that after cleaning high-permeability intervals of the bottom-hole zone from clay particles and other muds, not only the oil production rate of the well often increases, but the water cut of the well’s production also increases.

The proposed invention solves the problem of increasing the effectiveness of the impact due to the intensification of the claying process in low-permeability intervals of the formation, with the preliminary blockade of high-permeability intervals by polymer-alkaline solution.

The problem is solved in that in the method of claying out the bottomhole zone of a well, including injecting a claying composition, technological holding and development of a well, according to the invention, the claying composition is injected with two equal-sized rims, in the first rim, as a claying composition (wt.%):

surfactant (ML-81B) 0.1-2 sodium hydroxide 0.1-5 water soluble polymer (PAA, CMC) 0.05-5 water rest

in the second rim, as a proppant, a composition is used that includes (wt.%):

surfactant (ML-81B) 0.1-2 sodium hydroxide 0.1-5 water rest

SUMMARY OF THE INVENTION

In well-known technical solutions, when a proppant is injected into the bottomhole zone, it mainly penetrates into the highly permeable part of the formation and affects the clay material. The low permeability portion of the formation remains unaffected. The proposed method solves the problem of increasing the effectiveness of wedging of the bottomhole zone of the well due to the intensification of the process in low-permeable intervals of the formation. The problem is solved as follows.

When claying down the bottom-hole zone of a well, the claying composition is injected with two rims equal in volume. In turn, each rim can consist of several servings of the injected composition. In the first rim, as a proppant, use: (wt.%): 0.1-2 ML-81B surfactant, 0.1-5 sodium hydroxide, 0.05-5 water-soluble polymer and the rest is water. In the second rim, as a proppant, use (wt.%): 0.1-2 ML-81B surfactant, 0.1-5 sodium hydroxide and the rest is water.

The composition of the first rim has a high viscosity due to the presence of a water-soluble polymer, therefore, when injected, it penetrates mainly into highly permeable zones and blocks them. The polymer is adsorbed on the walls of the pore channels and cracks in the form of a film attracting water. Therefore, water present in highly permeable intervals, when moving near this film, will slow down due to its attraction by the polymer. The polymer molecules adsorbed in the pore channels and cracks will repel oil (or gas) from themselves, which contributes to their flow through the central part of the pore. The polymer film in the pores creates an additional friction force for water, which it must overcome and at the same time serves as a lubricant for the movement of oil.

Since the aqueous polymer solution is pumped in an alkaline medium with a high pH value, the polymer in the reservoir conditions will swell and reliably block water.

The polymer present in the composition also serves as a moderator of the wedging process. Due to what, loosening in highly-permeable zones is slower, and with small technological shutter speeds, and not completely.

The composition of the second rim, injected next, has a low viscosity and penetrates mainly into low-permeability zones, since the high-permeability intervals are blocked by the polymer-alkaline composition of the first rim. As a result of loosening, the low-permeability zones are freed from the clay mud material and their permeability increases.

After pumping out the claying composition, technological shutter speed is carried out to go through the claying process and well development.

As a result, the effectiveness of the wining process is increased.

Concrete example

Example 1. During the claying of the bottom-hole zone of an oil well, injection of claying material is organized by two rims of equal volume. In the first rim, as a proppant, a composition is used that includes, (wt.%): 0.1 of the ML-81B surfactant, 0.1 sodium hydroxide, 0.05 water-soluble polymer - polyacrylamide and the rest - water. The volume of the first rim is 6 m ³ . In the second rim, as a proppant, a composition is used that includes, (wt.%): 0.1 of the surfactant ML-81B, 0.1 sodium hydroxide and the rest is water. The volume of the second rim is 6 m ³ .

After injecting the rims, technological endurance is carried out to pass the process of loosening within 24 hours and the well is mastered by swabbing.

Example 2. Perform, as example 1. In the first rim, as a proppant, a composition is used that includes (wt.%) 2 surfactants ML-81B, 5 sodium hydroxide, 5 water-soluble polymer - carboxymethyl cellulose and the rest - water. The volume of the first rim is 6 m ³ . In the second rim, as a proppant, a composition is used that includes (wt.%): 2 ML-81B surfactants, 5 sodium hydroxide, and the rest is water. The volume of the second rim is 6 m ³ .

After injecting the rims, technological endurance is carried out to go through the claying process for 24 hours and the well is mastered by the operation of a sucker rod pump.

Example 3. Perform, as example 1. In the first rim as a proppant, use a composition comprising (wt.%) 1 surfactant ML-81B, 3 sodium hydroxide, 3 water-soluble polymer - carboxymethyl cellulose and the rest - water. The volume of the first rim is 6 m ³ . In the second rim, as a proppant, a composition is used that includes (wt.%): 1 ML-81B surfactant, 3 sodium hydroxide, and the rest is water. The volume of the second rim is 6 m ³ .

After injecting the rims, technological endurance is carried out to go through the claying process for 24 hours and the well is mastered by the operation of a sucker rod pump.

As a result, the wells according to examples 1-3 after mudding have a fluid flow rate of the order of 4-5 m ³ / day, while flow rates before claying are 1-2 m ³ / day. Conducting claying on similar wells according to the prototype leads to an increase in flow rate to 3-4 m ³ / day.

The application of the proposed method will solve the problem of increasing the effectiveness of wedging due to the intensification of the process in low-permeability intervals of the reservoir.

Claims (1)

A method of claying out the bottom-hole zone of a well, including injecting a clay material, process holding and developing a well, characterized in that the clay is injected with two equal-sized rims; in the first rim, a clay composition is used as a clay material, wt.%: 0.1 -2 of the surfactant ML-81B, 0.1-5 sodium hydroxide, 0.05-5 water-soluble polymer and the rest is water, in the second rim, as a proppant, use a composition including . Ayuschy, wt%: 0.1-2 surfactant-ML 81B, 0.1-5 sodium hydroxide and the rest - water.