SU1670095A1 - Method of well cementing - Google Patents

Abstract

The invention relates to the construction of wells. The purpose of the invention is to improve the quality of cementing by increasing the durability of the cement stone. The layers with aggressive fluids are treated with a calmatant - lime suspension, then the casing is lowered and the annulus is plugged. The formations are treated by squeezing the slurry in them, and the amount of slurry should provide compensation for the cement stone contraction. The method is compatible with the use of various grouting cements. 2 tab.

Description

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The invention relates to the construction of wells and can be used to mount wells with casing.

The purpose of the invention is to improve the quality of cementing by increasing the durability of the cement stone.

The goal is achieved by treating coals with strata with aggressive reservoir fluids, lowering the casing and plugging the annulus, and using a lime slurry as clogging agent.

The essence of the invention is that it provides the most favorable conditions for the hardening of the cement slurry, namely the solution hardens in contact with the lime suspension. In this case, if a contraction occurs when the cement stone is hardening into the inward-moving cement stone, a lime suspension is sucked in, and not an aggressive formation fluid. In this case, it becomes possible to increase the reaction capacity of the well lining by saturation of the formation with a lime suspension, which neutralizes it. before penetration to the cement stone, which leads to an increase in the durability of the stone.

The method is carried out as follows.

A casing with the necessary tooling complex is conducted into the drilled well. According to the data of geophysical studies, the boundaries of the layers are identified, the fluid of which contains aggressive components. After the well has been washed, a portion of the lime suspension is pumped through the casing and the subsequent injection of the washing fluid is forced through the limestone.

J o o you ate

Penza in the annulus in such a way that it is located against the reservoir containing an aggressive fluid. After that, the annular space is closed and, injecting washing fluid into the casing or annulus, crush the lime suspension into the reservoir. Then the cement slurry is injected into the casing, forced into the annulus and left to the RFQ.

The method can be implemented in another way. In this case, the bottom of the casing string is equipped with devices that allow to intensify the penetration of the suspension into the formation, for example, with an oscillator. The casing string is lowered into the well to the middle or bottom of the formation with aggressive fluid and intermediate flushing of the well is carried out. During this flushing, a calcareous suspension is injected through the casing, which is trapped through the casing shoe into the reservoir, after which the remaining casing continues to descend the casing. After complete descent of the column, it is subjected to tampo- and amorphous circulation.

The verification method was carried out as follows. Artificial sand cores with a porosity of 50 ... 55% were made, which are cylinders with a length of 40 mm and a diameter of 40 mm. The cores were impregnated with an aggressive solution (0.1N HCl solution), then cement slurry prepared from Portland cement (W / C 0.45) was poured on them with the help of formwork. Before pouring the cement slurry according to the proposed method, the cores on the casting side were saturated with lime suspension in an amount of 10 cm 3. After 24 hours of exposure to air

the formwork was removed, the side surfaces of the core and the cement stone were covered with epoxy resin so that the aggressor would penetrate to the cement stone only through the core. After the epoxy had cured, the samples were immersed in aggressive 0.1N, HCI solution. After certain periods of time, the samples were removed from the solution, sawn along and along the change

the colors of the corroded sample zone determined the depth of corrosion. Control samples were made similarly. but without saturating the cores with lime suspension.

The results of the experiments are given

in table.1.

As can be seen from the experimental results, when processing cores with lime suspension, the rate and depth of corrosion

grouting stone is significantly reduced, and the durability increases accordingly.

Table 2 shows the test results with the treatment of the rock with a chalk or lime suspension.

The results show the high efficiency of the method when using different types of cement.

The use of the method will improve the longevity of lining wells

Claims (1)

The invention method of cementing wells, including treatment with an aqueous suspension clogging of formations with aggressive formation fluids, lowering the casing, plugging of the annulus, characterized in that, in order to improve the quality of cementing by increasing the durability of the cement stone, lime is used as a bonding agent. Table 1 Reservoir treatment Cement is formed at T ° C PCT-D20-50 (20iS) Lime-cement-earthy cement (120 ° С) ШПЦС-200 (160 ° С) Alinite cement (20 ° С) PCT-D20-50 (20 ° С) Lime-lime cement (120 ° С) ШПЦС-200 (160 ° С) Alinite cement 20 ° С Table 2 The depth of cement stone damage when exposed to dissolved H2S, mm, less than 2 months of storage 2.0 / 10 4.0 / 15 3.0 / 18 2.0 / 8 O / o About / About About / About About / About