METHOD OF BOTTOM-HOLE STRENGTHENING OF WELLS WITH PER FORMATIONS IN UNSETTLED CEMENT SLURRY
11th International Multidisciplinary Scientific GeoConference SGEM2011, www.sgem.org, SGEM2011 Conference Proceedings/ ISSN 1314-2704, June 20-25, 2011, Vol. 1, 1229-1236 pp
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, destroys 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 zones 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 prevents dilution of cement mortar
with squeezing liquid (process water) and provides fixation of punched channels in a
hardening solution. At the moment of punching 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 takes 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 column of the liquid in the well is prevents
efflux of flushing fluid.
Pressure of the initiated blast wave at the 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 punched projectiles, creates conditions for
consolidation of grouting solution and separation of excess water that provides
formation of a cement stone with high strength and optimum 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.
Keywords: bottom-hole, casing method, cement slurry, wells, calcium chloride
PAPER 2011/s05.102: METHOD OF BOTTOM-HOLE STRENGTHENING OF WELLS WITH PER FORMATIONS IN UNSETTLED CEMENT SLURRY
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