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METHOD OF BOTTOM-HOLE STRENGTHENING OF WELLS WITH PER FORMATIONS IN UNSETTLED CEMENT SLURRY

D. K. Baiseit

Abstract

The main shortcoming of the earlier offered casing methods was the fact that along with the productivity slowdown of a well, in some cases there was observed renewing of sanding, with even greater intensity. Renewal of sand production after the carried out casing is explained by the specificity of cement stone perforation, in the production process of which a part of projectiles remain in layer of a cement stone, and the other, with the influence on a productive layer, dest roys it, forming new caverns. In addition, detonation of a punch charge in a cement stone and on the contact of a cement stone with a column causes the formation of cracks and channels. The casing method of bottom-hole formation z ones include filling of cement mortar to well, squeezing it into a layer by means of viscous-plastic fluid and perforation of producing interval which is offered to be produced till the curing of cement mortar. Availability viscous-plastic fluid as a buffer element preven ts dilution of cement mortar with squeezing liquid (process water) and provides fixation of punched channels in a hardening solution. At the moment of punc hing the flushing fluid (that is not in perforation channels as they have not been created yet) is pushed aside by pressure of gases both from grouting solution and in it At the moment of rupture of charge of gunpowder separation of flushing fluid take s place (not losing the viscous-plasctic properties) to the border with the solution and in channels at the appearance of channels the flushing fluid occupies a cavity of channels before they start to deform under weight of abovementioned rocks and cement that is caused by the fact that cement forcedly passes to the solid state, and hydrostatic colu mn of the liquid in the well is prevents efflux of flushing fluid. Pressure of the initiated blast wave at th e perforation not hardened cement mortar causes better penetration of the latter into cracks and caverns, increase of contact bond grouting material with the layer rock. Considerably directed pressure difference, formed at combustion of a powder charge of punc hed projectiles, creates conditions for consolidation of grouting solution and separation of excess water that provides formation of a cement stone with high strength and optim um filtration indicators. Explosive character of pressure rise considerably reduces terms setting (hardening) of grouting solution, and in the presence of calcium chloride in 1-6 % amount leads to a forced passing of a solution to solid state.

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DOI resolver: doi.org/10.5593/sgem2011/s05.102

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