RU2194844C2 - Base of weighted plugging mortar - Google Patents

Abstract

FIELD: plugging mortars used in cementing of casing strings of oil and gas wells in interval of abnormally high formation pressures and temperatures from 22 to 120 C. SUBSTANCE: base of weighted plugging mortar includes oil-well portland cement with regulator of processing properties and weighting additive in the form of Magbar weighting additive presenting homogeneous mixture of mas.pt. of magnetite and 1 mas.pt. of barite with the following ratio of ingredients, wt.%: portland cement, 25-40; Magbar, 60-75; regulator of processing properties, 0-4 of portland cement weight. Base of weighted plugging mortar may contain expanding additive of magnesium oxide MgO, calcium oxide CaO, gypsum in amount of 0-4% of portland cement weight. Regulator of processing properties may be used in the form of reducer of plugging mortar water loss - sulfocell, carboxymethyl cellulose in amount of 0-1.0% of portland cement weight, or reagents in the form of retarders-plasticizers nitrilotrimethylenephosphoric acid NTF, C-3 in amount of 0-0.5% of portland cement weight. Technical result of said invention consists in trouble-free cementing of casing strings in zone of abnormally high formation pressure, brine, mineralized water, fresh water due to higher sedimentation stability, earlier strength of plugging stone within wide temperature range from 35 to 120 C, high density up to 2.5 g/cu.cm with simultaneous provision of the remaining parameters of mortar and stone such as water loss, pumpability, resistance to corrosion. EFFECT: higher efficiency. 4 cl, 4 tbl, 1 ex

Description

The invention relates to grouting compositions used in cementing casing strings of oil and gas wells in the range of abnormally high formation pressures (AHP) and temperatures from 22 to 120 ^o C.

 Known weighted grouting composition containing Portland cement, slag and a weighting additive - iron ore concentrate (UTsG, USTs) (Novokhatsky DF Special grouting materials, Drilling, 6, M. 1972, p. 14).

 Known weighted grouting mortar, including Portland cement, a weighting additive and water (cement, barite 50:50) (Grouting mixtures for wells with abnormal pressures., Karimov N.Kh., Khakhaev B.N. et al. M.: Nedra, 1977 city of p. 97).

A disadvantage of the known weighted solutions is premature thickening, a decrease in pumping time, a large sludge - sedimentation instability of the system and a decrease in density to 2.2 g / cm ³ .

 The closest of the analogues is the base of a heavier grouting mortar consisting of Portland cement, a weighting additive and a setting agent reagent. RF patent 2109924, Е 21 В 33/138, 2000

The disadvantages of this base weighted grouting mortar are large water separation (up to 2.0%) - sedimentation instability, low adhesion, low strength characteristics of the groutstone at temperatures up to 75 ^o C, foaming of the solution during its preparation.

The objective of the invention is to create the basis of a heavy cement slurry, ensuring a trouble-free cementing process for casing strings in the zone of abnormally high formation pressures, brines, saline water, fresh water by increasing sedimentation stability, early cement slurry strength over a wide temperature range from 35 to 120 ^o С, high density - 2.5 g / cm ^3, while ensuring the remaining solution and technological parameters stone - fluid loss, pumpability, adhesion, corrosion with oykost.

This goal is achieved due to the fact that the base of the heavier grouting mortar, including grouting Portland cement with a technological properties regulator and a weighting additive, contains Magbar as a weighting additive, which represents a homogeneous mixture of 1 wt.h. magnetite and 1 parts by weight barite in the following ratios of ingredients, wt.%:
Specified Portland cement - 25-40
Magbar - 60-75
Regulator of technological properties - 0-4% by weight of Portland cement
The basis of a heavy cement slurry as a regulator of technological properties may contain an expanding additive of magnesium oxide MgO, calcium oxide CaO, gypsum in an amount of 0-4% by weight of Portland cement.

 The basis of a heavier grouting mortar as a regulator of technological properties may contain sulfocell grouting fluid loss reducer, carboxymethyl cellulose - CMC in an amount of 0-1.0% by weight of Portland cement.

 The basis of a heavy grouting mortar as a regulator of technological properties contains moderator reagents - plasticizers nitrilotrimethylene phosphonic acid NTF, C-3 in an amount of 0-0.5% by weight of Portland cement.

 The basis of the heavier grouting mortar contains a fluid loss reducer of grouting sulphacell grout, CMC or other reagents in an amount of 0 to 1.0% by weight of cement.

 The basis of the heavy cement slurry contains retarders, plasticizers NTF, S-3, etc. in the amount of 0-0.5% by weight of cement.

Barite-magnetite weighting compound (Magbar) based on the Lebedinsky GOK of iron ore concentrate is manufactured according to TU 39-00147001-185-99 at the Ilsky plant "Weighting" at JSC "NPO" Burenie "(AS 1006468 and AS 1213060) Designed to neutralize hydrogen sulfide and increase the density of drilling fluids when drilling oil and gas wells. Magbar has a density of 4.4 g / cm ³ .

In the present invention, Magbar makes it possible to obtain a sedimentation-resistant weighted grouting mortar with zero water sludge, overlapping saline, hay-producing and fresh horizons with AWP having a dynamic temperature of 35-50 ^o C and above, with stone strength and adhesion to the rock and pipe and the density of the mortar is higher 2.5 g / cm ³ .

 The basis of the weighted grouting mortar is prepared by thoroughly mixing the grouting Portland cement (PTC) and Magbar, and, if necessary, regulators of technological properties. For example, experiment 8, table. 3: 30.0 g of Portland cement + 70.0 g of Magbar. The preparation of a homogeneous base of a heavier grouting composition can be carried out both in the factory and in well conditions. When preparing the basis of a heavy grouting mortar, a three-time repacking of the prepared mixture is necessary. As regulators of the technological properties of the base of a heavy grouting mortar, fluid loss reducers, accelerators, moderators, and expanding additives can be used. These regulators can be entered at the stage of preparation of the base at the factory or during the preparation of the solution in the well.

The determination of the basic properties of a weighted grouting mortar and stone is carried out in accordance with GOSTs. "Cement grouting", Test methods. "Determination of density, spreadability, water separation is carried out at 20 ± 2 ^o C and atmospheric pressure.

For conditions of moderate temperatures, tests are carried out at 75 ^o C and atmospheric pressure. For the conditions of automatic pressure transfer - at temperatures of 100-140 ^o C and a pressure of 50 MPa. Spreadability is determined by the cone of the AzNII, the density of the pycnometer, the coefficient of water separation in the graduated cylinder, the setting time with a Vika needle, the thickening time on the KC-3 consistometer, the strength of the stone during bending and compression on the MII-100 testing machine and the PSU-10 press.

 Example. To prepare 1 kg of a weighted solution (composition 6, table. 2) 400 g of PTC are mixed with 600 g of Magbar and the resulting dry mixture is closed with a mixing liquid (salt mixture 3) in a known manner. The composition is stirred for 3 minutes, after which the density, spreadability, and setting time are determined.

 The stone is tested for strength after 24 hours of hardening at operating temperatures and pressure.

The test results are given in table. 1-4. The density of the solution is 2.44 g / cm ³ , the setting time at 22 ^o C: 9 h 40 m - the beginning, 11 h 00 m - the end.

For cementing columns that overlap saline and brine-developing horizons having dynamic temperatures of 35-50 ^o C, salt solutions of compositions 1, 2, 3 of different densities are proposed as mixing liquids.

As can be seen from the table. 2, 3, with the ratio of PCT: Magbar (30-25) :( 70:75) the density of the cement slurry can be increased to 2.57 g / cm ³ .

Strength in bending of cement stone at a temperature of 22 ^o C after 2 days. is 0.9-1.3 MPa, and at a temperature of 35 ^o C - 0.9-1.8 MPa, at a temperature of 50 ^o C - 0.9-1.4 MPa.

When the content of the weighted cement slurry is 40% PCT, the density of the solution is below 2.5 g / cm ³ .

 Moderator reagents are selected based on the required setting time and thickening time.

The proposed base of a heavy cement slurry can improve the quality of deep well attachment and prevent gas and oil occurrences that occur when cementing casing strings in areas of abnormally high reservoir pressures in the temperature range from 20 to 120 ^o C due to the high sedimentation stability, adhesion and adjustable technological properties of the mortar and stone .

 The invention contains know-how.

Claims (3)

1. The basis of the weighted grouting mortar, including grouting Portland cement with process controllers and a weighting additive, characterized in that it contains Magbar as a weighting additive, which is a homogeneous mixture of 1 parts by weight of magnetite and 1 parts by weight of barite in the following ratios of ingredients wt. %:
Specified Portland cement - 25-40
Magbar - 60-75
Regulators of technological properties - 0-4 by weight of Portland cement
2. The basis of the weighted grouting mortar according to claim 1, characterized in that as a regulator of technological properties it contains an expanding additive of magnesium oxide MgO, calcium oxide CaO, gypsum in an amount of 0-4% by weight of Portland cement.  3. The basis of the weighted grouting mortar according to claim 1 or 2, characterized in that it contains a sulfocell grouting fluid loss reducer, CMC carboxymethyl cellulose in an amount of 0-1.0% by weight of Portland cement as a regulator of technological properties.  4. The basis of the heavy grouting mortar according to claim 1, 2, or 3, characterized in that it contains moderating agents as moderator of the technological properties — plasticizers nitrilotrimethylene phosphonic acid NTF, C-3 in an amount of 0-0.5% by weight of Portland cement .

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