RU2153572C1 - Method of strengthening well wall in drilling - Google Patents

Abstract

FIELD: oil-and-gas producing industry. SUBSTANCE: method relates to methods of preservation of reservoir properties of producing formation during their primary drilling. Method includes treatment of well wall with jet of drilling mud flowing out of side nozzle of colmatage sub and containing finely dispersed fraction in the form of finely dispersed hydrophobic material with particles sizing from 0.1 to 100 mcm. Said drilling mud is supplied to well wall surface layer at velocity of 70-80 m/s with its concentration of 0.02-0.03 wt.% during drilling in. Finely dispersed hydrophobic material may be used in the form of swollen graphite or white black, or aerosil, or perlite. Prior to supplying of finely dispersed hydrophobic material to drilling mud, it is mixed with oil and surfactant in the following ratio of components, wt.%: finely dispersed hydrophobic material, 0.02-0.03; oil, 10; surfactant, 0.01; drilling mud, the balance. EFFECT: strengthening of well wall in drilling due to increased efficiency of isolation of permeable formations at the moment of their primary drilling in. 3 cl, 1 dwg, 1 tbl

Description

 The invention relates to the oil and gas industry, in particular to methods for preserving the reservoir properties of productive formations during their initial opening.

 Currently, one of the reasons for the decrease in the production rates of newly drilled wells is formation pollution, associated in particular with uncontrolled penetration of drilling fluid filtrates and cement slurry into the bottomhole formation zone, which leads to the formation of stable oil-water emulsions and insoluble salt deposits blocking permeable intervals.

 There are various ways to reduce the penetration zone of the filtrate, in particular by creating a strong, insignificant in thickness, co-formation screen in the near-barrel zone of the formation immediately at the time of opening of the permeable formation.

 A known method of reducing the permeability of the reservoirs by treating the permeable wall of the well with mud jets of a mud while drilling at a fluid flow rate of 60-120 m / s (SU, a.s. N 819306, E 21 B 33/138, 04/07/1981).

 The closest technical solution to the proposed invention is the technology of hardening of the borehole wall during drilling at the stage of primary opening of the productive formations with their fluidization with mud monitored clay streams at the required flow rate of the flushing fluid (RU, patent N 2024729, E 21 B 33/138, 12/15/1994 ) According to this patent, a method of hardening a borehole wall while drilling consists in treating a borehole wall with a jet of washing liquid flowing out of a side nozzle of a clamming sub and containing a finely divided fraction.

 A common disadvantage of these methods is the low waterproofing characteristics of the mud layer formed in the borehole zone with a significant penetration depth of the filtrate.

 The problem to which the present invention is directed, is to develop a technology for strengthening the wall of a well during drilling by increasing the insulation efficiency of permeable formations at the time of their initial opening. The technical result consists in the fact that the well wall is treated with hydro-monitor jets of washing liquid containing finely divided hydrophobic material, as a result of which the natural degree of hydrophobicity of the pore surface of the reservoir increases. This leads to an increase in capillary pressures at the water-oil section and creates additional resistance to the displacement of oil deep into the reservoir under the influence of excess pressure of the flushing fluid.

 To achieve the above technical result in a method of hardening a borehole wall while drilling, comprising treating a borehole wall with a jet of washing liquid flowing out of a side nozzle of a clamming sub and containing a finely divided fraction, which is used as a finely dispersed hydrophobic material with particle sizes from 0.1 to 100 microns , which is fed to the surface layer of the wall of the well when opening the reservoir at a speed of 70 - 80 m / s, while the concentration of finely dispersed hydrophobic material iala is selected from the range (wt.%) from 0.02 to 0.03.

Moreover, as a finely dispersed hydrophobic material, it is possible to use expanded graphite, or white soot, or aerosil, or talc, or perlite, and finely dispersed hydrophobic material is mixed with oil and a surfactant-surfactant in the following ratio (wt.%) ):
Fine hydrophobic material - 0.02 - 0.03
Oil - 10
Surfactant - 0,01
Wash Fluid - Else
The drawing shows a setup for treating a formation with finely dispersed hydrophobic material during an initial opening.

 The present invention is illustrated by a specific embodiment, which, however, is not the only possible, but clearly demonstrates the possibility of achieving this set of features of a given technical result.

 Processing a productive section at the time of opening is performed by exposing a well of a jet of washing fluid containing finely dispersed hydrophobic material to the well walls that flows from the side nozzle of the clogging sub with a speed of 70 - 80 m / s. The boundary values of the initial rate of penetration of hydrophobic material into the surface layer of the well wall are determined by the depth of their penetration and, as a result, the effectiveness of the strengthening of the well wall and the efficiency of the process.

 At the same time, the hydrophobic material, penetrating into the pores of the oil-saturated permeable formation, creates the conditions for the formation of a durable, insignificant hydrophobic mud layer on the well wall, which prevents the penetration of the filtrate of the drilling fluid and cement mortar at further stages of well construction. In addition, hydrophobic particles from 0.1 to 100 microns in size, adsorbing on the surface of clay collector materials, form a hydrophobic barrier that prevents them from contacting with filtrates and reduces their hydration. As a finely dispersed hydrophobic material, the material manufactured according to RF patent N 2089499, or expanded graphite, or white soot, or aerosil, or talc, or perlite, is used.

 A uniform distribution of finely divided hydrophobic powdery material throughout the volume of the solution is achieved by pre-mixing it in oil with a small amount of washing liquid and adding a surfactant such as a surfactant, such as neonol. The concentrated suspension prepared in this way is introduced by the pump into the discharge line of the drilling rig when opening a productive section.

 The washing liquid formulation, its parameters and material concentration are selected individually in each case, depending on the expected reservoir characteristics of the section being opened, the effective thickness of the formations, and the presence of washed and water-saturated zones.

As a device for implementing the method of strengthening the wall of a well during drilling, an installation (see drawing) can be used, which contains a mixing chamber 1, into which finely dispersed powdered hydrophobic material, surfactant, and oil from an oil tanker are supplied together with a flushing fluid in a strictly defined ratio 2. Before feeding finely dispersed hydrophobic material in the washing liquid is mixed with oil and surfactant in the following ratio, wt.%:
Fine hydrophobic material - 0.02 - 0.03
Oil - 10
Surfactant - 0,01
Wash Fluid - Else
Perlite was introduced into the composition as a finely dispersed hydrophobic material, and neonol as a surfactant.

 In the mixing chamber 1, the components are intensively mixed, after which the suspension thus obtained by means of a pump 3, for example a cementing unit, is fed into the discharge line 4, into which clay solution is supplied via pipeline 5.

 Clay solution treated with a suspension of finely divided hydrophobic powdery material, surfactant and oil enters the drilling tool 6, then into the collimator 7, installed after the bit 8 along the tool while drilling the well.

 The results of processing the surface layer of the borehole wall during the initial opening of the reservoir are shown in the table.

 It follows from the table that, as a result of the use of finely dispersed hydrophobic material during the initial opening of productive formations, the indicators related to permeability, productivity and oil recovery are higher than similar indicators of base wells.

 The invention meets the condition of "industrial applicability", since it is feasible using existing means of production using known technologies.

Claims (3)

 1. A method of hardening a borehole wall while drilling, comprising treating a borehole wall with a jet of washing fluid flowing out of a side nozzle of a clamming sub and containing a finely dispersed fraction, characterized in that finely dispersed hydrophobic material with a particle size of 0.1-100 microns is used as a finely dispersed fraction, which is fed to the surface layer of the well wall when opening the reservoir at a speed of 70 - 80 m / s, while the concentration of finely dispersed hydrophobic material is selected from the range it is 0.02 - 0.03 wt.%.  2. The method according to claim 1, characterized in that as a finely dispersed hydrophobic material, expanded graphite, or white soot, or aerosil, or talc, or perlite can be used. 3. The method according to claim 1, characterized in that the finely divided hydrophobic material is mixed with oil and a surfactant — surfactant — in the following ratio, wt.%:
Fine hydrophobic material - 0.02 - 0.03
Oil - 10
Surfactant - 0,01
Wash Fluid - Else

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