RU2224881C2 - Method for extracting high-viscous and heavy oil deposits - Google Patents

Abstract

FIELD: oil extracting industry. SUBSTANCE: method includes consecutive pumping of calculated amount of heat carrier and thermostable surface- active substance into the well. Well is kept closed for predetermined amount of time. Before pumping surface-active substance into the layer extraction area is additionally heated by heat carrier. Then 0.5-0.7% of mass of water solution of surface-active substance is pumped in portions. Amount of pumped substance is determined from analytical expression. Surface-active substance is pumped into the layer by means of heat carrier. EFFECT: increased oil output during extraction of high-viscous and heavy oil deposits. 1 cl, 1 ex

Description

The invention relates to the oil industry, in particular, to the development of deposits of highly viscous and heavy oils by thermal methods in combination with various additives, for example surfactants.

A known method of exposure to formations containing heavy hydrocarbons, steam [ser. Oil field business. 21, Moscow: VNIIOENG, 1983, p. 64].

The disadvantage of this method is the low coefficient of extraction of heavy oils due to steam breakthrough to production wells in the most permeable interlayers, vapor migration under the influence of gravitational forces into the upper layers of the reservoir, as well as condensation, resulting in heat, to reduce the viscosity of bitumen and break the adhesive contact between bitumen and sandstone is not enough.

The closest in technical essence and the achieved result to the proposed is a method of developing deposits of high viscosity and heavy oils [see US Pat. RU No. 2163292, Е 21 В 43/24, publ. bull. No. 5, 2001], including the sequential injection of a coolant and a thermostable surfactant into the well, extraction of oil from the well, and after the calculated amount of coolant has been pumped, the well can withstand a certain time in the closed state, moreover, the RDN reagent system, which is a composition, is used as a surfactant consisting of a nonionic surfactant (nonionic surfactant), a concentrate of polar, high molecular weight asphalt-resinous and paraffin components (ASPK) oil and an aromatic hydrocarbon solvent, in which it is effective o dissolves both nonionic surfactants and ASPK.

The method allows to slightly increase the efficiency of oil displacement during the heat and steam treatment of the formation by increasing the coverage of the formation.

The disadvantage of this method is the low efficiency of displacement due to the instability of a thermostable emulsion-disperse system of the direct type based on the RDN, depending both on the operating parameters of the injection and on the components of the formation itself. In addition, a highly concentrated RDN reagent composition is used for injection, which entails increased material costs.

The technical task to be solved is to increase the efficiency of oil recovery during the development of viscous and heavy oil fields under the sequential action of a heat carrier and a thermostable surfactant.

The stated technical problem is achieved by the described method, including sequential injection of the calculated amount of coolant and thermostable surfactant into the well, holding the well for a certain time in the closed state.

New is that before the surfactant is injected into the formation, the bottomhole zone of the well is additionally heated with a coolant, then a 05-0.7 wt.% Aqueous surfactant solution is injected portionwise, while the injection volume is determined by the formula:

V Zak. = 0.1 × V por = 0.1 x m × πh ³ , m ³ , where

m - formation porosity,%;

h is the thickness of the working part of the reservoir, m,

moreover, the surfactant rim is pressed into the formation by the heat carrier, steam is used as the heat carrier, and the detergents “MS-1” or “MV-1” are used as the surfactant.

The claimed combination of distinctive features allows to increase the efficiency of oil recovery by combining thermal and physico-chemical effects. In this case, the adhesion contact between high-viscosity, heavy oils and sandstone is destroyed. Aqueous solutions of thermostable surfactants introduced into the formation together with steam have a low surface tension, improve wetting, promote hydrophilization of the pores of the formation as a whole, change capillary forces and improve the mobility (bitumen) of heavy oils.

Squeezing surfactant rims into the reservoir with steam promotes the formation of a stable foam that covers part of the large pore channels, which causes a redistribution of the filtration paths and leads to the active movement of bitumen along low-permeable sections of the formation, which, in turn, increases the coverage of the formation by thermal exposure and, ultimately , improves oil recovery.

Of the available sources of patent and scientific literature, the claimed combination of distinctive features is unknown. Therefore, the proposed method meets the criterion of "inventive step".

The method is carried out in the following sequence (combined with an example of a specific implementation).

The method was tested on deposits of bitumen occurring in terrigenous reservoirs developed by the method of thermocyclic impact (TWC) on the reservoir by steam, the reservoir in which are characterized by the following parameters:

1) the depth of the bed, m - 70-120;

2) bitumen-saturated thickness, not less than m - 3;

3) permeability, not less, microns ² - 0.5;

4) porosity, not less than,% - 18;

5) bitumen saturation, not less than,% of the pore volume - 40;

5) pressure of injection of agents, no more, MPa - 5;

6) the temperature of the coolant, ° C - 100 ° C.

When testing used the following reagents:

1) detergent MS-1, containing anionic surfactants (alkylarisulfonate or alkyl sulfate), carboxymethyl cellulose, sodium sulfate, alkyl amides, sodium tripolyphosphate in certain proportions - GOST-25644-96;

2) detergent MV-1 containing sulfonol (sulfonate) - TU-6-01-862-75, sodium metasilicate - GOST-13078-81, caustic soda - GOST-11078-78, soda ash - GOST-5100-85 in certain ratios, which are produced by the industry of the Republic of Tatarstan, they are non-existent, inexpensive, convenient for working in field conditions and approved for use in accordance with the "Regulation on the procedure for admitting to use chemical products intended for use in the extraction, transportation and refining of oil" approved by the Gosgortekhnadzor of Russia.

Detergents were pumped using standard wellhead equipment, mechanisms and assemblies used in well overhauls:

1) portable compressors SD 9/101 (TU26-12-67 383) or stationary installations OVG-75 / 70U;

2) tankers for transportation of industrial water - ЦП-500, ЦР-7АП;

3) a mobile peeling unit CA-320 M type;

4) mobile PPU-3M steam generators;

5) station SKT-1, SKT-2.

Production wells were selected for injection, the water cut of which was not more than 90%.

The well selected for the injection of detergent was equipped with a research site, a manometer, a thermometer and a tap for sampling liquid and gas.

Before starting work, we carried out a set of geophysical studies to study the technical condition of the production casing and identify ways to filter water and bitumen, determine the values of reservoir and bottomhole pressures and temperatures.

The working concentration of aqueous solutions of detergents is 05-0.7 wt.%.

In wells selected for injection of a detergent solution, by injection of 3-4 m ³ hot water (t≥70 ° C) or cold (depending on the temperature in the formation), the interval of injectivity of the formation was determined, the flow rate of the well and the water cut of the produced products were measured, samples of formation fluid and gases were taken for analysis.

The volume of injection was carried out according to the above formula. The calculated volume of the aqueous solution of detergent was prepared at the place of use in tankers or in measured tanks of the cementing unit CA-320 M in portions of 5-6 m ^{3 of the} solution in a given concentration, then it was fed into the measured tank of the unit and diluted with technical water with vigorous stirring for 10-15 minutes The finished detergent solution was pumped into the reservoir (RD 39 - 0147585 - 122 - 95).

Accounting for injection volumes was carried out by measuring capacities of the unit.

Before the injection of detergents, the bottom-hole zone of the well was additionally heated with steam.

Steam was injected through the tubing string in a volume of 40-80 t with a flow rate of 3-5 t / h according to RD-39-R-27-90 BO VNII. At the same time, in order to prevent heating of the casing string and mixing of the injected solution from the compressors, air was injected at a flow rate of 500-600 m ³ / h.

An aqueous solution of detergent was injected through the tubing string with a closed annulus. After the detergent was pumped into the bottom-hole zone heated by steam, the steam was pushed into the formation in a volume equal to 0.5 of the detergent injection volume.

Detergent solution was injected with a minimum supply of the unit, the maximum pressure during the injection process in order to avoid formation rupture should not exceed 0.8 P _r (P _r - rock pressure).

After pumping the estimated volume of the detergent solution and pushing it into the formation, the well was closed for thermocapillary impregnation and for the redistribution of the detergent solution in the formation. Well exposure continued until the temperature in the bottomhole zone of the well decreased to 70-90 ° C.

Then the well was put into operation and fluid was sampled until the flow to the wellhead ceased.

After stopping the selection of heavy oil, the next cycle was carried out to inject steam into the bottomhole zone, etc.

The experimental work showed that the set of distinctive features in the proposed method when heating the bottom-hole zone with steam (40-80 t), injecting an aqueous solution of 0.5-0.7% concentration of detergent "MS-1" or "MB-1" in the amount determined for a particular well and pushing this solution with steam in an amount of 0.5 of the volume of detergent injected into the formation allows to increase the displacement coefficient to 52-53% and reduce water cut by six times.

Claims (2)

1. A method of developing highly viscous and heavy oil fields, including sequentially injecting the calculated amount of coolant and thermostable surfactant into the well, holding the well for a certain time in the closed state, characterized in that the bottom-hole zone of the well is additionally heated before the surfactant is injected into the formation coolant, then 0.5-0.7 wt.% aqueous surfactant solution is injected portionwise, while the injection volume is determined by the formulas V _Zak. = 0.1 × V _pore = 0.1 × m × πh ³ , m ³ , where m is the porosity of the reservoir,%; h is the thickness of the working part of the reservoir, m, moreover, the surfactant rim is pressed into the formation with a coolant. 2. The method according to p. 1, characterized in that steam is used as a heat carrier, and "MS-1" or "MB-1" detergents are used as a surfactant.