SU1546612A1 - Method of isolating formation water in well - Google Patents

Description

The invention relates to the oil and gas industry. The goal is to improve the quality of insulation while simplifying the method. In the well down and cement the casing. In the process of cementing, a cavity is formed in the wall by changing the direction of movement of the cement slurry in the annular space, and horizontal cracks are formed and filled with cement mortar. To prevent fracturing of rocks when filling cracks in the process of cementing, they limit the rate of injection by known methods. 3 il.

The invention relates to the oil and gas industry, in particular to methods of isolation of formation water.

The purpose of the invention is to improve the quality of insulation while simplifying the method.

The essence of the method lies in the fact that the casing string is lowered and cemented into the well and form caverns and horizontal cracks along the cavity in the well wall, fill the cavity and the resulting horizontal cracks with cement mortar. the interval of the annular space of the well, i.e. ensures the preservation of 'technological operations.

FIG. 1 shows a wellbore section prior to casing cementing; in fig. 2 - the same, in the process tse

mantings; in fig. 3 - the same, in the process of formation of the screen in the borehole wall.

The method is implemented as follows.

After the completion of the well drilling, geophysical studies are carried out, the depth of the oil and aquifer formations and the actual diameter of the well are determined. A casing 1 is lowered into a well to a depth of 2200 m (FIG. 1), on which the flow diverter 2 is fixed. The diverter 2 is located in the range of 3 between the aquifer 4 and oil

• 5 layers. Carry out cementing, during which the fluid moving in the annulus of the well due to the installation of the flow diverter 2, change the direction of motion, act on the well wall and form a cavity in it
• 6 (FIG. 2), in which the arrows indicate the direction of movement of liquids. The required volume of cement, determined by the actual diameter of the well, will be 55 m ³ . 60 m ^{3 of} cement slurry is pumped into the well in such a way that the extra 5 m ^{3 of the} mortar goes

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to fill the cavity formed at the end of the cementing process in the well wall and the resulting horizontal cracks. As cement mortar is pumped, the hydrostatic pressure in the annulus of the well increases. The resulting stresses are concentrated at the top of the formed cavity 6, at the end of cementing the hydrostatic pressure of the liquid column 7 (FIG. 3) exceeds the allowable fracture pressure of the rocks, hydraulic fracturing occurs in the cavity and the horizontal cracks 8 are filled with cement mortar. To prevent premature fracturing during the cementing process, the injection rates are limited by known

techniques.

Claims (1)

Claim five The method of isolation of formation water in the well, including the descent and cementing of the casing, the formation in the well wall of the cavity and horizontal fractures and the subsequent filling of the latter with a cement mortar, characterized in that, in order to improve the quality of the insulation while simplifying the method cementing by changing the direction of movement of the cement slurry in the annular space. FIG. 2 1546612