RU2491314C2 - Grouting mortar of selective action - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to oil and gas industry, in particular to methods of selective isolation of water influxes in gas and oil wells, sealing of hole clearance, elimination of inter-strata inter-flows in wells with closely located gas-oil-water contact, including conditions of low-permeability reservoirs. Grouting mortar of selective action contains, wt %: fine-ground cement Microdur 33.83-36.96, hydrocarbon carrier - Diesel fuel 57.51- 62.84, de-emulsifier-separol 0.20-2.35, hardening activator aluminium sulphate or iron sulphate, or potassium carbonate 0-8.22.

EFFECT: extension of application field and increase of reliability and efficiency of grouting due to improvement of technological possibilities of grouting mortar and increased filtering capability into low-permeability reservoirs, micro-clearances and microcracks.

2 cl, 2 tbl

Description

The invention relates to the oil and gas industry, in particular to methods for the selective isolation of water inflows in gas and oil wells, sealing the annulus, eliminating interstratal flows in wells with a close gas-oil contact, including in low-permeability reservoirs.

A known composition for the isolation of water flows (V. S. Danyushevsky and others. "Reference guide for cementing materials." - M .: "Nedra", 1987, p. 187), which is a cement mixture consisting of cement, diesel fuel - 30- 50%, surfactant (cresol) - 0.5-1.0% and a powder accelerator (soda ash) - 6%. The mixture can be obtained by partial or complete replacement of cement with gypsum.

The disadvantages of this mixture are:

- low strength of the formed cement stone;

- poor replacement of diesel fuel with water.

A known composition for the selective isolation of waterlogged zones of the reservoir according to St. St. USSR No. 857450 in the following ratio of components, wt.%:

a polymer from the group of polyolefins 40-70, semi-aqueous calcium sulfate 30-60.

The disadvantages of this composition is:

narrow area of use and low efficiency of insulation work, due to:

- insufficiently high penetrating ability into the channels and pores of the insulating layer due to unsatisfactory rheological properties;

- low sedimentation stability and strength of the created water-resistant partitions.

The closest in technological essence is the cement slurry "NCR HIMEKO-VMN" according to patent RU No. 2357999 with the following content of components, wt.%: Hydraulic binder - 70-85, surfactant - surfactant "ADB" - 0.1-0 , 2, surfactant Neftenol VKS-N - 0.1-0.3, the hydrocarbon phase - the rest. As a hydraulic binder can be used cement, Portland cement - PTsT-1, PTs-2, gypsum building. As the hydrocarbon phase can be applied: diesel fuel, refined (anhydrous) oil, gas condensate.

The disadvantages of this grouting mortar are:

- a narrow area of use, due to limited penetration in low-permeability reservoirs, which follows from the ratio of hydraulic binder and hydrocarbon phase 70-85 / 30-15, tabular data on density, spreadability. The indicated ratio and the data in the table show that a binder with a specific surface of ~ 300 m ² / kg was used, which roughly corresponds to particle sizes of 25-60 microns, which cannot be pumped into low-permeability collectors;

- the formation of an emulsion in contact with formation water.

The technical result of the invention is to expand the scope and increase the reliability and efficiency of grouting by improving the technological capabilities of grouting mortar and increased filtering ability in low-permeability reservoirs, micro-gaps and microcracks.

This technical result is achieved by solving the problem aimed at creating a cement slurry with a binder having a high specific surface, which should have particles no larger than 2-4 microns in size, which will allow changing the ratio of solid to liquid in the direction of liquid predominance, which will increase its penetrating ability .

The mixing fluid (carrier) should be a contrasting fluid with respect to formation water, compatible with oil, but in an aqueous environment should be demulsified as much as possible with a demulsifier added to the solution, in addition, cementitious hardening activators can be added to the solution: aluminum sulfate, iron sulfate or potassium carbonate.

The technical problem is solved in that the cement slurry of selective action includes a binder, a hydrocarbon carrier - diesel fuel, a demulsifier - separol, a hardening activator - aluminum sulfate or iron sulfate or potassium carbonate, and as a binder - finely ground cement Microdur in the following ratio of components, wt .%:

fine cement Microdur 36.96-33.83 hydrocarbon carrier - diesel fuel 62.84-5 demulsifier separol 0.20-2.35 hardening activator - aluminum sulfate or iron sulfate or potassium carbonate 0-8.22

The essence of the invention lies in the fact that the cement slurry of selective action containing a binder, a hydrocarbon carrier - diesel fuel, additionally contains demulsifier-separol, hardening activator - aluminum sulfate or iron sulfate or potassium carbonate, and as a binder - finely ground cement Microdur.

Of the known finely ground binders, Microdur obtained from Portland cement is the most effective.

In the proposed grouting mortar of selective action, highly finely ground cements, for example, Mikrodur, are used as a highly demanding finely dispersed binder. The binder “Mikrodur” is produced by air separation of dust generated by grinding cement clinker, the technology of its manufacture was developed and mastered by the specialists of the company “INTRA - BAVGmbH” together with the specialists of the concern “Dyckerhoff” and is protected by the European patent. The diameter of the Mikrodur grains is 6-10 times or more smaller than the particles of the cement clinker itself. Due to the small particle size (grain diameter ≤2-6 μm), high specific surface (20000-25000 cm ² / g) and smoothly selected particle size distribution, Mikrodur solutions have a fluidity comparable to that of water, even with a minimum amount of mixing liquid, which allows the suspension "Mikrodur" to penetrate deep into low permeable rock. The expiration time (conditional viscosity) of a suspension under the age of 3 hours ranges from 28 to 30 seconds.

In contrast to the prototype, the use of a finely dispersed binder Mikrodur allows you to more fully bind water and tighten the structure of the stone and thereby ensure its increased fluid resistance and durability. This is also due to the fact that finely dispersed binders are able to bind water many times more, since their water-solid ratio can reach 3.0-5.0 with a specific surface of 15000-25000 cm ² / g against 0.3-0.5 conventional grouting cements having a specific surface area of 3000-3500 cm ² / g.

Moreover, the addition of a binder of less than 33.83 wt.% Sharply reduces the strength of the formed stone, the addition of more than 36.96 wt.% Leads to a thickening of the composition.

In the cement slurry of selective action, a hydrocarbon carrier is used - diesel fuel, which allows Mikrodur and the demulsifier-separol to form a compact easily pumpable mass, which, when interacting with produced water, significantly (1.2-1.5 times) increases its volume. The addition of diesel fuel of less than 55.60 wt.% Makes it difficult to sell the composition into the reservoir, with the addition of more than 62.84 wt.% It dilutes the composition and reduces its ability to be fixed in the reservoir.

As a hydrocarbon carrier can also be used: gas condensate, refined (anhydrous) oil.

In a grouting mortar of selective action, an demulsifier additive, separol, is used. The addition of separol of less than 0.2 wt.% Does not contribute to the separation of diesel fuel in an aqueous reservoir environment. In this case, an unstable organomineral stone is formed. The addition of a demulsifier of more than 2.35 wt.% Leads to premature setting of the insulating composition.

The hardening activator used is necessary at low temperatures. With additives of more than 8.22 wt.% It can cause the injected composition into the formation to early thickening. As a hardening activator, aluminum sulfate or iron sulfate or potassium carbonate is used.

The preparation of cement slurry of selective action is carried out directly at the well. Grouting mortar of selective action is prepared in the usual way using a clay mixer or aggregate-mixing machine, for example, ASM-25, (USO-20), in which the components are sequentially introduced: diesel fuel, demulsifier, binder, hardening activator.

Determination of the basic properties of the mortar and stone is carried out in accordance with GOST 1581-96 "Cement grouting" and GOST 26798.1-96 "Test methods". Determination of density, flowability is carried out at 22 ° C and atmospheric pressure. For conditions of moderate temperatures, the tests are carried out at 70-90 ° C and atmospheric pressure, for the conditions of the automatic air flow test at temperatures up to 120 ° C and a pressure of 60 MPa. Spreadability is determined by the cone of the AzNII, the density of the pycnometer, the beginning of setting with the addition of water using a Vika device, the strength using a hydraulic press.

When conducting laboratory tests were used:

- tap water;

- Microdur;

- diesel fuel;

- separol;

- hardening activator - aluminum sulfate, iron sulfate, potassium carbonate.

Example

To prepare a cement slurry of selective action (composition 12, Table 1), 2.6 g (2 cm ³ ) (0.96 mass%) of separol are added to diesel fuel in a volume of 200 cm ³ (62.36 wt.%) Sequentially 100 g (36.68 wt.%) Microdur. We mix the composition for 3 minutes, after which we determine the spreadability, density. Then we add formation water of 100 cm ³ , mixing the composition for 3 min and measuring the spreadability, setting time, sediment of diesel fuel, strength after 2 days.

The test results are shown in table 1. For composition 12, the density of the solution is 1.18 g / cm ³ , the spreadability is 22 cm, the setting time is> 8-00 hours, the sediment is 45%, the strength is 4.08 kg / cm ² at 22 ° C.

The advantages of the proposed cement slurry selective action:

- expanding the scope and increasing the efficiency of grouting by improving the technological capabilities of the grouting mixture, simplifying its preparation in field conditions and increased filtering ability in low-permeability reservoirs, micro-gaps and microcracks.

The economic effect of the use of the inventive cement slurry will be determined by increasing the productivity of the repaired wells.

Claims (1)

Grouting mortar of selective action, including an astringent, hydrocarbon carrier - diesel fuel, characterized in that it additionally contains demulsifier - separol, hardening activator aluminum sulfate or iron sulfate, or potassium carbonate, and as a binder - finely ground cement Microdur in the following ratio of components, wt .%:
fine cement Microdur 33.83-36.96 hydrocarbon carrier - diesel fuel 57.51-62.84 demulsifier - separol 0.20-2.35 hardening activator aluminum sulfate or iron sulfate, or potassium carbonate 0-8.22