SU1677270A1 - Method to combat non-organic salt deposits at the bottomhole and oil well equipment - Google Patents

Abstract

The invention relates to the oil industry. The purpose of the invention is to increase the efficiency of the method by uniformly delivering the inhibitor from the formation to the well while reducing the overhead of the inhibitor. The required volume of the inhibitor solution is pumped into the treated formation, then the buffer fluid in the volume of not less than 0.5 of the volume of the water isolating agent; water isolating agent in the volume of 0.05-0.10 m per 1 m of the exposed thickness of the reservoir, again the buffer fluid in the amount of not less than 0.5 of the volume of the water isolating agent, then pumped the liquid to push the agents deep into the reservoir. The well is closed for 12 hours. The volume of the squeezing fluid is determined by the depth of the squeeze into the reservoir. The use of this method ensures a uniform consumption of the inhibitor in time and an increase in the period of time between the treatment of wells with scaling inhibitors.

Description

The invention relates to the oil industry and can be used in production wells that are subjected to the deposition of inorganic salts in the bottomhole formation zone and underground equipment during the production of flooded oil.

The purpose of the invention is to increase the efficiency of the method due to the uniform flow of the inhibitor from the formation into the well while reducing the overhead costs of the inhibitor.

In the method of combating the deposition of salts in the bottomhole formation zone and equipment of oilfield wells, including the injection of an inhibitor solution into the well,

selling its liquid, shutting down the well and putting it into operation, after pumping the inhibitor solution, supplying the buffer fluid, water-insulating reagent, re-buffering fluid, and pushing the listed reagents into the formation with the squeezing fluid. As a buffer liquid, it is necessary to use reagents that do not interact with the used salt scavenger and water insulating reagent, in particular, anhydrous organic solvents or petroleum products, for example, lower aliphatic alcohols, which are fatty alcohols or their mixtures, separate hydrocarbon fractions, and anhydrous oil.

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Water, aqueous solutions of salts, and oil may be used as the squeezing fluid.

When treating a well after injection of the inhibitor solution, in order to reduce its losses in the first days after treatment and prolong the removal time in quantities that provide protection against scaling, it is isolated with a supply of water-insulating reagent. In addition, between the inhibitor solution and the water insulating reagent and after it, a buffer fluid is used that does not interact with the scale inhibitor and water insulating reagent used to prevent their mixing.

In this method, the water isolating agent, pumped after the inhibitor solution and the buffer fluid, is used to create an effective isolation shield in relation to the desorption removal of the inhibitor by partially reducing the permeability of the aquifer. The creation of such an insulating screen contributes to the time delay of the inhibitor in the reservoir, which increases its removal time due to the uniform removal of the reagent and reduction of losses in the first days after treatment.

In the method, due to the creation of an insulating screen, the unproductive losses of the inhibitor are reduced in the first days after treatment, when the inhibitor is removed in quantities that provide protection against scaling. Due to this, the protective effect increases without increasing its consumption by about 1.3 times (see table).

It is the selected sequence of operations that provides the most effective protection of oilfield equipment by reducing the inhibitor losses in the first days after treatment and extending the inhibitor removal time in quantities that provide protection against salt deposition, and reduces the specific consumption of the scale inhibitor.

The method is carried out as follows.

The required volume of the inhibitor solution is pumped into the treated formation, then a buffer fluid in a volume of not less than 0.5 of the volume of the water isolating agent, a water isolating agent in a volume of 0.05-0.10 m3 per 1 m of the exposed thickness of the formation, again the buffer fluid in a volume not less than 0.5 of the volume of the water isolating agent, then pump the fluid to push the reagents into the reservoir. After the crowding, the well is closed for 12 hours.

squeezing fluid is determined by the depth of squeezing into the formation.

Example. The studies were carried out on the installation Model reservoir. The installation is made in the form of a chamber filled with a crushed core field, a BVV (sandstone) formation of a fraction from 0.1 to 1.00 mm, weighing about 200 g. The core was compressed with a rubber casing using a press, which simulates rock pressure and is achieved its permeability is close to the permeability of sandstone in reservoir conditions. A solution was used as an inhibitor.

5 inhibitors of salt deposition of PAF-13A at concentrations of 3 and 6%. Initially, the core was saturated with distilled water to determine the volume of the pore space. Hence, determine whether the total required

0 the volume of the injected fluid so that it provides for the injection of the inhibitor solution, the buffer fluid and the water reagent into the core. The water reagent used was a pe5 agent based on oligoorganoethoxychloroxyloxanes - the brand name of the product is 119-204. Product 119-204 was diluted with acetone in a 1: 1 ratio. Preliminary studies have been carried out to determine

0 optimal dilution of product 119-204 in acetone. Experiments have shown that this ratio is 1: 1. Anhydrous oil was used as a buffer and flow liquid.

5 A solution of the PAF-13A inhibitor, a buffer fluid, a water insulating reagent, a buffer fluid, a squeezing fluid was crushed successively with a press into the chamber with increased pressure,

0 countercurrent flow of filtering fluid. After pressing the solutions, the installation was stopped and left under pressure for 12 hours. This time is sufficient to adsorb the inhibitor and polymerize

5 product.

After aging, the inhibitor was desorbed with distilled water. The flow rate and speed of water movement was regulated by variable hydraulic resistance. In the collected samples, the inhibitor was determined by photocolorimetric method. For comparison, similar studies of inhibitor desorption without the use of a water insulating reagent

5 of the prototype.

The duration of the protective effect was determined by the volume of the liquid, after pumping which the content of inhibitor in the pumped liquid is not lower than 0.5 mg / l - the extremely low concentration of inhibitor in the liquid necessary to effectively prevent scaling.

The test results and the calculated values of the optimal injection volume of the water insulating agent are given in the table.

It follows from the table that, according to the proposed method, the reduction of inhibitor losses in the first samples is significantly compared with the prototype, hence the duration of the protective effect of the inhibitor increases by 1.3 times.

Using the method of treatment of wells prone to the deposition of salts, provides compared with the known uniform consumption of the inhibitor in time; an increase in the time period between well treatment with scale inhibitors. Average well protection time is 175 days.

Claims (1)

The invention of the method of controlling inorganic salt deposits in the near-wellbore formation zone and equipment of an oil well, including the injection of an inhibitor solution into the well, pushing it into the formation with a squeezing fluid, holding the well and putting it into operation, characterized in that due to the uniform flow of the inhibitor from the reservoir into the well while reducing the non-productive costs of the inhibitor, anhydrous water is additionally sequentially pumped into the well before pushing into the reservoir ernuyu liquid water shutoff reagent and buffer liquid anhydrous, wherein the water shutoff reagent is injected in a volume 0,05-0.10 m3 per 1 m thickness of the exposed layer, and an anhydrous liquid buffer - in the amount not less than 0.5 times the volume of water shutoff agent. High content in inhibitor samples Optimal content and uniform removal of inhibitor Ditto Low content Same High content of inhibitor in samples High content of inhibitor in samples Close to the optimal content of the inhibitor. Same Uneven removal of the inhibitor Same High content of inhibitors in samples