RU2172814C2 - Method of stabilization of bottom-hole formation zone - Google Patents

Abstract

FIELD: technique and technology of well remedial work, particularly, methods of formation of annular- space filter in producing formation of oil, water and gas wells. SUBSTANCE: method includes preparation of grouting mortar with acid-soluble filler, its injection and setting, drilling out, flushing of formed stone from salt. Acid-soluble filler is used in form of shell rock of 0.7-1.5-mm fraction in amount of 10-15 wt.%. Introduced additionally into grouting mortar is surfactant in amount of 0.5-1.0 wt.%. EFFECT: prevented clogging of bottom- hole zone due to injection of stable and plastic grouting mortar. 1 tbl

Description

 The present invention relates to techniques and technologies for underground well repair, and in particular to methods for creating an annular filter in a reservoir of oil, water and gas wells.

 A known method of fastening the bottom-hole zone of the well, including the descent of the casing string, the injection of cement slurry, its hardening and perforation of the string [1].

 The disadvantage of this method is that silt slurry and sand enter the well from the reservoir with weakly cemented rock through the perforation channels, and this leads to clogging of the channels and, as a result, to the shutdown of the well.

 The closest in technical essence and the achieved result to the proposed technical solution is a method of fixing the bottom hole of the well, including the preparation and injection into the reservoir through perforation channels of a cement slurry consisting of cement, sand, salt and a soluble filler of calcium carbonate - chalk. The cement slurry is prepared on a salt basis (2).

 However, this method does not provide the formation of high-quality permeability of the bottomhole zone due to the lack of stability of the cement slurry when pumping it into the reservoir.

 The solid phase of the cement slurry (cement, sand) settles when moving along the wellbore, the solution is heterogeneous. As a result of this, there is no formation of a solid and durable cement stone, the solution does not pass into the pores (channels) of the rock, and as a result, a filtering cement stone is not created throughout the column in the reservoir, and as a result, the rock consisting of the smallest particles is removed from the reservoir (siltstone). The well is plugged, and the reservoir product does not enter the wellhead.

 In addition, the presence of salt in the grouting mortar as the main material forming the filter for the well product increases the curing time of the prepared grouting mortar into stone and reduces its crushing strength, while there is no plasticity of the grouting mortar.

 So the use of such a solution in the well N 64 "Beisug" of the Krasnodar Territory field failed to eliminate the removal of siltstone rock.

 The aim of the invention is to prevent clogging of the bottomhole zone by pumping a stable and plastic cement slurry.

 This goal is achieved by the fact that non-ionic surfactant is additionally added to the cement-based cement slurry in a quantity of from 0.5 to 1.0% (wt.), And a shell rock of fraction 0 is introduced as a soluble filler of calcium carbonate , 7-1.5 mm in an amount of 10-15% (weight.).

 The method includes preparing a grouting solution based on salt, pumping it into the well, penetrating the solution into the pores (channels) of the rock, curing it (formation of cement stone), drilling, washing the formed stone from salt.

 A non-ionic surfactant is additionally introduced into the cement grout based on salt, for example: dissolvan - 4411, neonol, proxamine - 385, reanon - 413, etc., which ensures the stability and uniformity of the solution after mixing. At the same time, the cement slurry acquires a plasticity property, and this ensures its penetration into the pores (channels) of the rock, which contributes to the qualitative fastening of the bottomhole zone of the well and does not clog the pores (channels) of the rock.

 In addition, non-ionic surfactants accelerate the curing time of cement slurry in the bottomhole zone and increase the strength properties of the resulting cement stone for compression in the reservoir.

 The use of nonionic surfactants in the preparation of cement slurry allows the use of industrial water instead of saline. At the same time, the fractional size of salt entering the industrial water remains practically unchanged, which ensures the necessary permeability of cement stone in the bottomhole zone after salt washing and acceleration of the curing time of grouting mortar.

 A shell rock is introduced into the grouting cement mortar as a soluble filler, which is well destroyed in the cement stone during acid treatment, the need for which may arise if the necessary permeability of the cement stone is not achieved when salt is washed out.

 The optimal interval fraction of the introduced shell rock is 0.7-1.5. If fractions of less than 0.7 are added, the pores formed in the cement stone will be small and the permeability of the stone will be low, and if fractions of more than 1.5 are introduced, the pores formed will be large and the permeability of the cement stone will be too high. The optimal amount of shell rock injected is 10-15% (weight.). With the introduction of a shell rock of less than 10%, an insufficient number of pores will form in the cement stone, and with the introduction of more than 15% a large number of pores will increase the permeability of the cement stone.

 Shell rock is much cheaper and more affordable in purchase as a natural material.

 The proposed method of fixing the bottom-hole zone with cement grout containing cement, sand, salt, shell rock, a surfactant (dissolvan - 4411, neonol, etc.), allows to identify distinctive features in comparison with the prototype, which allows us to establish the conformity of the proposed method with the criterion " novelty".

Laboratory studies of fastening the bottom-hole zone of the well by the proposed method, in which a grouting mortar of the following composition was prepared, (wt.%):
Grouting cement - 50
Sand (fraction 0.3-1.5 mm) - 10
Shell rock (fraction 0.7-1.5 mm) - 10
Salt (fraction 2-3 mm) - 10
Nonionic surfactant (dissolvan 4411, neonol) - 1.0
Water - - The rest (until the fluidity of the solution is 18-20 cm along the cone of the AZNII)
The optimal results for the use of nonionic surfactants (dissolvan 4411, neonol) were obtained with its introduction in an amount of from 0.5 to 1.0%.

 The introduction of a non-ionic surfactant into the grouting mortar of less than 0.5% is not sufficient to obtain the desired parameters of the cement stone, and the introduction of a surfactant into the grouting mortar of more than 1.0% is impractical, since it does not significantly increase the properties of the cement stone.

 Comparative results of fastening the bottom-hole zone according to the prototype and the proposed method are summarized in table.

 The table shows that the proposed technical solution allows to reduce the curing time of cement stone, to increase its permeability and compressive strength.

 Using the proposed method will prevent clogging of the bottomhole zone of the well and use cheaper components for the preparation of grouting mortar.

Sources of information:
1. A. B. Suleymanov et al. Technique and technology for overhaul of wells. Moscow, "Nedra", 1987, p. 28-33.

 2. RF patent N 2005165 according to class. E 21 B 33/138, 1993, BI N 47.

Claims (1)

 A method of attaching a bottomhole zone of a well, including preparing a cement slurry with an acid-soluble filler, pumping it and curing, drilling, washing the formed stone from salt, characterized in that a shell rock of a fraction of 0.7-1.5 mm in an amount of 10- is used as an acid-soluble filler 15 wt.% And additionally in the grouting solution, a surfactant is introduced in an amount of 0.5-1.0 wt.%.

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