Well flushing fluid for wax-containing oil well and preparation method of well flushing fluid

Abstract

The invention discloses a flushing fluid for a wax-containing oil well and a preparation method of the flushing fluid. The cleaning agent is characterized by comprising the following raw material components in percentage by mass: 4-5% of a zwitterionic surfactant, 5-7% of an anionic / nonionic surfactant, 7-10% of an anionic surfactant, 5-7% of a nonionic surfactant and 71-79% of water, and the sum of the contents of the raw materials is 100%. The problems that in the prior art, due to the fact that hot water well washing is large in leakage amount, reservoir damage is caused, the well washing efficiency is low, and the oil breakthrough period is long are solved, the performance of the well washing agent is obviously superior to that of hot water well washing, adaptability is high, the well washing agent can be applied to well washing maintenance operation of wax-bearing oil wells, well washing time is shortened, and well washing efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of well-washing fluids, and relates to well-washing fluids for waxy oil wells. The invention also relates to a preparation method of the well-washing fluids for waxy oil wells. Background Art

[0002] During the production process of oil wells in oil fields, wax will form on the inner and outer walls of the oil pipes, and well washing maintenance is required to maintain the normal production of the oil wells. Conventional hot water well washing has problems such as large leakage, reservoir damage, low well washing efficiency, and long oil recovery period. Therefore, it is necessary to find a more effective well washing fluid and its preparation method to solve the problems existing in the prior art of large leakage, reservoir damage, low well washing efficiency, and long oil recovery period caused by hot water well washing. Summary of the invention

[0003] The purpose of the present invention is to provide a well-washing fluid for waxy oil wells, which solves the problem of large leakage in hot water well-washing in the prior art.

[0004] Another object of the present invention is to provide a method for preparing the above-mentioned well washing fluid for waxy oil wells.

[0005] The technical solution adopted by the present invention is that the well washing fluid used for waxy oil wells is composed of the following raw material components according to mass percentage:

[0006] Zwitterionic surfactant 4%-5%, anionic nonionic surfactant 5%-7%, anionic surfactant 7%-10%, nonionic surfactant 5%-7%, water 71%-79%, the total content of the above raw materials is 100%.

[0007] The present invention is also characterized in that the zwitterionic surfactant is an alkyl hydroxysulfonyl betaine, wherein the carbon number C of the alkyl group is 12-18.

[0008] The present invention is also characterized in that the anionic nonionic surfactant is sodium polyoxyethylene propylene alkyl sulfonate, the carbon number C is 8-10, the propylene chain PO is 1-5, and the ethylene chain EO is 1-10.

[0009] The present invention is also characterized in that the anionic surfactant is sodium alkylbenzene sulfonate, and the carbon number C of the alkyl group is 10-13.

[0010] The present invention is also characterized in that the nonionic surfactant is fatty alcohol polyoxyethylene ether, the carbon number of the alkyl group is 12-18, and the ethylene chain EO is 9-20.

[0011] Another technical solution adopted by the present invention is a method for preparing a well washing fluid for a waxy oil well, which is specifically implemented according to the following steps:

[0012] Step 1: Weigh the following raw materials by mass percentage:

[0013] 4% to 5% of zwitterionic surfactant, 5% to 7% of anionic nonionic surfactant, 7% to 10% of anionic surfactant, 5% to 7% of nonionic surfactant, and 71% to 79% of water, the total content of the above raw materials is 100%;

[0014] Step 2: Add the weighed raw materials into a reaction kettle, stir and heat to 55-65°C;

[0015] Step 3: After stirring at a constant temperature of 55-65° C. for 29-31 minutes, stop heating and cool to room temperature to obtain a well washing fluid.

[0016] The beneficial effects of the present invention are: solving the problems existing in the prior art of reservoir damage, low well washing efficiency and long oil-seeping period caused by large leakage in hot water well washing, and the performance of the present invention is obviously better than that of hot water well washing, with strong adaptability, and can be applied to the well washing maintenance operation of waxy oil wells, thereby reducing the well washing time and improving the well washing efficiency. DETAILED DESCRIPTION

[0017] The present invention is described in detail below in conjunction with specific implementation modes.

[0018] The invention provides a well washing fluid for waxy oil wells, which is composed of the following raw material components by mass percentage: 4% to 5% of amphoteric surfactant, 5% to 7% of anionic nonionic surfactant, 7% to 10% of anionic surfactant, 5% to 7% of nonionic surfactant, and 71% to 79% of water, and the total mass of the above components is 100%.

[0019] The present invention provides a well washing fluid for waxy oil wells and a preparation method thereof, which is specifically implemented according to the following steps:

[0020] Step 1, weighing the following raw materials respectively by mass percentage: 4% to 5% of zwitterionic surfactant, 5% to 7% of anionic nonionic surfactant, 7% to 10% of anionic surfactant, 5% to 7% of nonionic surfactant, and 71% to 79% of water, the sum of the contents of the above raw materials being 100%;

[0021] Step 2, adding the weighed raw materials into a reaction kettle, stirring and heating to 55-65° C.;

[0022] Step 3, after stirring at a constant temperature of 55-65° C. for 30 minutes, stop heating, and after cooling to room temperature, obtain a well washing liquid.

[0023] A well washing fluid for waxy oil wells of the present invention was tested, and the results are as follows: the well washing fluid for waxy oil wells of the present invention is a solution in a macroscopic state, is easy to use, has performance significantly better than that of existing hot water, has strong adaptability, can be used in well washing maintenance operations of waxy oil wells, shortens the flowback cycle by more than 37%, and extends the well washing cycle by more than 25%.

[0024] Embodiment 1:

[0025] A washing fluid for waxy oil wells and a preparation method thereof, comprising the following raw materials by mass percentage: 4% of zwitterionic surfactant; 7% of anionic nonionic surfactant; 7% of anionic surfactant; 7% of nonionic surfactant; and 75% of water.

[0026] The above-mentioned well washing fluid for waxy oil wells and its preparation method:

[0027] 4 parts by mass of zwitterionic surfactant, 7 parts by mass of anionic nonionic surfactant, 7 parts by mass of anionic surfactant, 7 parts by mass of nonionic surfactant and 75 parts by mass of water were added into a reactor, stirred and heated to 55° C., stirred at a constant temperature of 55° C. for 30 minutes, stopped heating, and cooled to room temperature to obtain a well washing fluid.

[0028] The prepared well washing fluid has an interfacial tension of 0.009 mN / m for crude oil in oil wells containing 17% wax, an oil removal rate of 95%, and a viscosity reduction rate of 96%. It has been used in 28 wells on site, and the load difference of the dynamometer diagram before and after well washing has decreased. Compared with hot water well washing, the return flow cycle has been shortened by 50% from 4 days to 2 days on average, and the well washing cycle has been reduced from 9 times / year to 6 times / year, extending the well washing cycle by 33%.

[0029] Embodiment 2:

[0030] A waxy oil well washing fluid and a preparation method thereof, comprising the following raw materials by mass percentage: 5% of a zwitterionic surfactant; 6% of anionic nonionic surfactant; 6% of anionic surfactant; 6% of nonionic surfactant; and 77% of water.

[0031] The above-mentioned one is used for the waxy oil well washing fluid and its preparation method:

[0032] 5 parts by mass of zwitterionic surfactant, 6 parts by mass of anionic nonionic surfactant, 6 parts by mass of anionic surfactant, 6 parts by mass of nonionic surfactant and 77 parts by mass of water were added into a reactor, stirred and heated to 60°C, stirred at a constant temperature of 60°C for 30 minutes, stopped heating, and cooled to room temperature to obtain a well washing fluid.

[0033] The prepared well washing fluid has an interfacial tension of 0.006 mN / m for crude oil in oil wells containing 15% wax, an oil removal rate of 98%, and a viscosity reduction rate of 94%. It was applied to 10 wells on site, and the load difference of the dynamometer diagram before and after well washing was reduced. Compared with hot water well washing, the return flow period was shortened by 37.5% from 4 days to 2.5 days on average, and the well washing period was reduced from 9.6 times / year to 6.6 times / year on average, extending the well washing period by 31.25%.

[0034] Embodiment 3:

[0035] A waxy oil well washing fluid and a preparation method thereof, comprising the following raw materials by mass percentage: 4% of a zwitterionic surfactant; 5% of anionic nonionic surfactant; 7% of anionic surfactant; 5% of nonionic surfactant; and 79% of water.

[0036] The above-mentioned one is used for the waxy oil well washing fluid and its preparation method:

[0037] 4 parts by mass of zwitterionic surfactant, 5 parts by mass of anionic nonionic surfactant, 7 parts by mass of anionic surfactant, 5 parts by mass of nonionic surfactant and 79 parts by mass of water were added into a reactor, stirred and heated to 65°C, stirred at a constant temperature of 65°C for 30 minutes, stopped heating, and cooled to room temperature to obtain a well washing fluid.

[0038] The prepared well washing fluid has an interfacial tension of 0.005 mN / m for crude oil in oil wells containing 10% wax, an oil removal rate of 99%, and a viscosity reduction rate of 96%. It has been used in 27 wells on site, and the load difference of the dynamometer diagram before and after well washing has decreased. Compared with hot water well washing, the return flow cycle has been reduced from 5 days to 3 days on average, which is 40% shorter. The well washing cycle has been reduced from 8 times / year to 6 times / year, which is 25% longer.

Claims

1. A well-washing fluid for waxy oil wells, characterized in that: The raw material components are as follows according to mass percentage: Zwitterionic surfactant 4%-5%, anionic nonionic surfactant 5%-7%, anionic surfactant 7%-10%, nonionic surfactant 5%-7%, water 71%-79%, the total content of the above raw materials is 100%.

2. The well washing fluid for waxy oil wells according to claim 1, characterized in that: The zwitterionic surfactant is an alkyl hydroxysulfonyl betaine, wherein the carbon number C of the alkyl group is 12-18.

3. The well washing fluid for waxy oil wells according to claim 1, characterized in that: The anionic nonionic surfactant is sodium polyoxyethylene propylene alkyl sulfonate, with a carbon number C of 8 to 10, a propylene chain PO of 1 to 5, and an ethylene chain EO of 1 to 10.

4. The well washing fluid for waxy oil wells according to claim 1, characterized in that: The anionic surfactant is sodium alkylbenzene sulfonate, and the carbon number C of the alkyl group is 10-13.

5. The well washing fluid for waxy oil wells according to claim 1, characterized in that: The nonionic surfactant is fatty alcohol polyoxyethylene ether, the carbon number of the alkyl group is 12-18, and the ethylene chain EO is 9-20.

6. A method for preparing a well-washing fluid for a waxy oil well, characterized in that: Follow the steps below to implement it: Step 1, weigh the following raw materials respectively by mass percentage: 4% to 5% of zwitterionic surfactant, 5% to 7% of anionic nonionic surfactant, 7% to 10% of anionic surfactant, 5% to 7% of nonionic surfactant, and 71% to 79% of water, the total content of the above raw materials is 100%; Step 2, adding the weighed raw materials into a reaction kettle, stirring and heating to 55-65° C.; Step 3, after stirring at a constant temperature of 55-65° C. for 30 minutes, stop heating, and after cooling to room temperature, obtain a well washing liquid.