CN1273997A

CN1273997A - Method for removing deposited dirt from oil well with chemical agent

Info

Publication number: CN1273997A
Application number: CN 99106847
Authority: CN
Inventors: 王素君; 田东恩; 刘和义; 关建华
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-17
Filing date: 1999-05-17
Publication date: 2000-11-22

Abstract

A method for removing wax deposit from oil well with chemical agents is disclosed. The chosen chemical agents are 25-45% aqueous solution of sodium nitrite, 30-50% aqueous solution of ammonium nitrate or ammonium chloride, catalyst (HAc), organic solvent (C9 or mixed benzene), mutual solvent (glycol or diglycol) and surfactant (T-20, OP-1, or OP-2). It is applied by loading them in sleeve tube of oil well. Its advantages are high safety and effect.

Description

Method for removing wax deposition of oil well by using chemical agent

The invention relates to a method for removing wax from an oil well, in particular to a method for removing wax deposition from an oil well by adopting a chemical agent.

Due to the existence of the earth temperature gradient, in the process that crude oil in the oil well pipe rises from a high-temperature stratum to a low-temperature stratum, heat is continuously transmitted to the low-temperature stratum, the oil temperature is reduced to be above a wax precipitation point, so that wax is precipitated on the wall of the oil well pipe and a near-well zone of an oil layer, in addition, a certain amount of gas is dissolved in the crude oil, when the gas is separated from the crude oil, the expansion speed of the gas is accelerated, a part of heat is absorbed, the temperature of the crude oil is reduced, and the wax precipitation also occurs. In order to remove the wax deposition, an electric or hand winch is generally used, a steel wire is connected with a wax removal lead head and a weighting rod to move up and down in an oil pipe so as to achieve the purpose of wax removal, and if the steel wire is broken, underground falling objects are easily caused, so that heavy loss is caused; the method is characterized in that hot water or steam is added with an active agent and circulated in a well to dissolve wax, clear water is formed in the process to soak an oil layer, the stratum is easily damaged, the yield is reduced or a water pumping recovery process needs a long time is needed, the method is low in heat energy utilization rate, the system is large in heat dissipation, and a large amount of heat energy is wasted.

The invention aims to provide a method for removing wax by utilizing heat and gas generated by chemical reaction of a chemical agent.

The chemical agents selected by the invention are as follows: the catalyst A is sodium nitrite aqueous solution with the concentration of 25-45%, the agent B is ammonium nitrate or ammonium chloride aqueous solution with the concentration of 30-50%, the agent C is composed of catalyst, organic solvent, surfactant and mutual solvent, the catalyst is HAc, the organic solvent is C9 or mixed benzene, the mutual solvent is ethylene glycol or diethylene glycol, the surfactant is T-20 and OP-1 or OP-2, the weight parts ratio of the components is: the A agent, the B agent, the catalyst, the organic solvent, the surfactant and the mutual solvent are as follows: 15-20: 15-30: 0.2-1: 35-45: 0.5-1.5: 8-12, and respectively adding the agent A, the agent B and the agent C into the oil well casing in any order for paraffin removal.

The agent A is preferably sodium nitrite aqueous solution with the concentration of 30-40%, and the agent B is preferably ammonium nitrate or ammonium chloride aqueous solution with the concentration of 35-45%. The preferable weight portion ratio of the agent A, the agent B, the catalyst, the organic solvent, the surfactant and the mutual solvent is as follows: 20-25: 0.2-1: 35-45: 0.5-1.5: 8-12.

The preparation method of the aqueous solution of the sodium nitrite which can be used as the agent A and the aqueous solution of the ammonium nitrate or the ammonium chloride which can be used as the agent B is well known in the chemical technical field, HAc and C9 in the agent C or mixed benzene, ethylene glycol or diethylene glycol, T-20 and OP-1 or OP-2 are common products, and the suspension liquid obtained by mixing the components is the agent C.

The chemical principle of the paraffin removal method of the invention is as follows: the heat generated by the reaction is used and is matched with an organic solvent, a mutual solvent, a surfactant and a catalyst, so that the wax is continuously dissolved to achieve the purpose of cleaning the wax, and in addition, the nitrogen generated by the reaction is also beneficial to cleaning the wax. The ammonium nitrate can be replaced by ammonium chloride, and the agent A, the agent B and the agent C are sequentially added into the oil well casing in any order for paraffin removal. The method is safe, efficient and low in cost.

The invention is illustrated in detail in the examples which follow, in which all percentages are by weight, unless otherwise indicated.

Example 1: 1 part of OP-1, 0.5 part of T-20, 8 parts of ethylene glycol, 42 parts of C9 and 1 part of HAc are prepared into emulsion, and the emulsion, 15 parts of 25% sodium nitrite solution and 15 parts of 50% ammonium nitrate solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 2: 1.5 parts of OP-1, 0.4 part of T-20, 10 parts of ethylene glycol, 35 parts of C9 and 1.2 parts of HAc are prepared into emulsion, and the emulsion, 20 parts of 30% sodium nitrite solution and 25 parts of 30% ammonium nitrate solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 3: 0.5 part of OP-1, 0.6 part of T-20, 12 parts of ethylene glycol, 45 parts of C9 and 0.8 part of HAc are prepared into emulsion, and the emulsion, 30 parts of 40% sodium nitrite solution and 30 parts of 40% ammonium nitrate solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 4: 1 part of OP-1, 0.1 part of T-20, 9 parts of ethylene glycol, 35 parts of C9 and 1 part of HAc are prepared into emulsion, and the emulsion, 20 parts of 45% sodium nitrite solution and 25 partsof 50% ammonium chloride solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 5: 1 part of OP-1, 0.1 part of T-20, 9 parts of ethylene glycol, 35 parts of C9 and 1 part of HAc are prepared into emulsion, and the emulsion, 20 parts of 45% sodium nitrite solution and 15 parts of 50% ammonium chloride solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 6: 1.5 parts of OP-1, 0.4 part of T-20, 10 parts of ethylene glycol, 35 parts of C9 and 1.2 parts of HAc are prepared into emulsion, and the emulsion, 20 parts of 30% sodium nitrite solution and 25 parts of 30% ammonium chloride solution are injected into an oil well casing in sequence to achieve the purpose of paraffin removal.

Example 7: 0.5 part of OP-1, 0.6 part of T-20, 12 parts of ethylene glycol, 45 parts of C9 and 0.8 part of HAc are prepared into emulsion, the emulsion, 30 parts of 40% ammonium chloride solution and 30 parts of 40% sodium nitrite solution are injected into an oil well casing in sequence, and the purpose of paraffin removal can be achieved.

Claims

1. A method for removing wax deposition of an oil well by adopting a chemical agent is characterized by comprising the following steps: the catalyst A is sodium nitrite aqueous solution with the concentration of 25-45%, the agent B is ammonium nitrate or ferric chloride aqueous solution with the concentration of 30-50%, the agent C is composed of catalyst, organic solvent, surfactant and mutual solvent, the catalyst is HAc, the organic solvent is C9 or mixed benzene, the mutual solvent is ethylene glycol or diethylene glycol, the surfactant is T-20 and OP-1 or OP-2, and the weight parts ratio of the components is as follows: the A agent, the B agent, the catalyst, the organic solvent, the surfactant and the mutual solvent are as follows: 15-20: 15-30: 0.2-1: 35-45: 0.5-1.5: 8-12, and respectively adding the agent A, the agent B and the agent C into the oil well casing in any order for paraffin removal.

2. The method for removing wax from oil well according to claim 1, wherein the agent A is an aqueous solution of sodium nitrite with a concentration of 30-40%, and the agent B is an aqueous solution of ammonium nitrate or ammonium chloride with a concentration of 35-45%.

3. The method for removing the wax deposition of the oil well according to the claim 1 or 2, characterized in that the weight parts ratio of the agent A, the agent B, the catalyst, the organic solvent, the surface active agent and the mutual solvent is as follows: 20-25: 0.2-1: 35-45: 0.5-1.5: 8-12.