RU2231535C1 - Method of preparing polymer-clay drilling fluid - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to drilling fluids used for boring vertical, inclined, and horizontal boreholes. Fluid is prepared by mechanically by stirring clay, Na₂CO₃, salt-resistant polymer (Dk-Drill or PraeStol-2540) and process water, for which purpose, first polymer solution is prepared and then clay is added. Fluid additionally contains carboxymethylcellulose (0.25-0.35%) and aluminum sulfate as stabilizing and structurization agent. Polymer solution is prepared by successively adding Na₂CO₃, carboxymethylcellulose, and polymer to water, while aluminum sulfate and clay are added in the form of suspension with density 1100-1120 kg/m³, which is weighted with chalk to desired density 1160-1350 kg/m³ and additionally treated with Na₂CO₃ and carboxymethylcellulose. Volume ratio of polymer solution to volume of suspension ranges from 1:0.75 to 1:5. Thus prepared frilling fluid contains, wt %: Na₂CO₃ 0.3-0.5, carboxymethylcellulose 0.25-0.35, salt-resistant polymer 0.05-0.15, Al₂(SO₄)₂ 0.012-0.015, water - the balance.

EFFECT: increased lifetime, improved technical and economical characteristics as well as quality of exposing productive formations.

Description

The invention relates to the field of drilling oil and gas wells, namely, drilling fluids used in the sinking of vertical, directional and horizontal wells.

Known polymer clay drilling fluid (1), the full description of which provides a method for its preparation, which consists in mechanically mixing the constituent components, such as clay, water and a stabilizing agent, while the waste of isopropyl alcohol production from the alcohol settling stage is taken as the latter - raw cheese and distillation of the epureate and additionally introduce caustic soda in the following ratio of components, wt.%: clay 10-30, waste from the production of isopropyl alcohol 5-30, caustic soda 0, 1-0.8, the rest is water.

The closest analogue is a method of preparing a polymer clay drilling mud (2) containing clay, a stabilizing agent, polyacrylamide, soda ash and water, with the following components, wt.%: Clay 40-60; polyacrylamide 0.018; soda ash 0.5; the rest of the water, by mechanical stirring of its constituent components, and first a polymer solution is prepared, then clay is introduced into it.

Common disadvantages of the above solutions are insufficient viability, i.e. the fragility of the prepared solutions by the above methods. This is explained by the fact that the known methods do not take into account complex well conditions during their implementation, and the prepared polymer clay solutions in an aggressive environment lose stability, and the restoration of rheological properties requires frequent additions of one or another necessary reagent. In addition, for the aforementioned reasons, they also do not have enough endurance of the cuttings, which leads to a decrease in the passability of the bit, especially when drilling directional and horizontal wells. The methods also do not take into account the use of prepared solutions when drilling productive formations by drilling.

The technical result of the invention is to provide a method of preparing a polymer clay drilling mud, providing increased vitality, taking into account downhole conditions and leading to improved technical and economic performance of drilling, as well as the quality of opening of reservoirs.

In the method of preparing a polymer clay mud by mechanical mixing of its constituent components: clay, soda ash Na ₂ CO _3, salt-resistant polymer in water, whereby the polymer solution is prepared, then clay is introduced into it, Dk-Drill is used as salt-resistant polymer or PraeStol-2540 as a water - process water and optionally a stabilizer cobuilder - CMC carboxymethyl cellulose and aluminum sulphate Al ₂ (SO _{4) 3,} a polymer solution was prepared by sequentially cc AH in industrial water Na ₂ CO _3, CMC, said polymer salt resistance, Al ₂ (SO _{4) 3,} clay is in the form of time-dispersed slurry density P = 1100-1120 kg / m ^3, chalk weighted to the desired density P = 1160 -1350 kg / m ³ , additionally treated with Na ₂ CO ₃ and CMC, in the ratio of Vp.:Vg.s = 1: 0.75-1: 5, where Vp.r is the volume of the polymer solution, m ³ , Vg. c - the volume of the indicated clay suspension, m ³ , in the following ratio of the components of the polymer solution, wt.%: Na ₂ CO ₃ 0.3–0.5, CMC 0.25–0.35, the specified salt-resistant polymer 0.05–0 , 15, Al ₂ (SO ₄ ) ₃ 0.012–0.015, process water the rest.

The introduction of soda ash into the polymer solution promotes the dissolution of CMC and provides stable bonds in the thixotropic composition, and aluminum sulfate Al ₃ (SO ₄ ) _{3 is} used for uniform crosslinking of the polymer.

The preparation of polymer clay drilling mud by the proposed method is as follows.

First, a polymer solution is prepared. To do this, the tank is filled with technical water. Then, with constant circular circulation, sequentially soda ash Na ₂ CO ₃ , CMC and a salt-resistant polymer like Dk Drill or PraeStol-2540 and aluminum sulfate Al ₃ (SO ₄ ) ₃ are introduced. The consumption of reagents for the preparation of an aqueous polymer solution is, kg / m ³ :

Na ₂ CO ₃ 3-5

CMC 2.5–3.5

Dk Drill or PraeStol-2540 0.5–1.5

Al ₂ (SO ₄ ) ₃ 0.12–0.15

Then, a pre-prepared clay suspension with a density of P = 1100-1120 kg / m ^{3 of} carefully dispersed clay in time in water in a clay factory or on the basis of production services is weighted with chalk to a density of 1160-1350 kg / m ³ . Then the finished clay-slurry suspension, treated with the necessary chemicals, for example, Na ₂ CO ₃ and CMC, is mixed with the polymer solution in the ratio Vp.:Vg.s = 1: 0.75-1: 5, where Vp.p is the volume of the polymer solution , m, Vg.s - the volume of clay clay suspension, m ³ .

Mixing clay-chalk suspension with a polymer solution can be carried out in well conditions according to the following scheme: capacity - mud pump - chanca CA - mud pump CA - capacity.

Example: The consumption of reagents for the preparation of an aqueous polymer solution is, wt.%: Na ₂ CO ₃ 0.5, CMC 0.25, PraeStol-2540 0.05, Al ₂ (SO ₄ ) ₃ 0.014, industrial water 99.186. Clay suspension is taken with a density of P = 1100 kg / m ³ , weighted with chalk to a density of 1160 kg / m ³ . Then the finished clay-slurry suspension treated with the necessary chemicals, for example Na ₂ CO ₃ and CMC, is mixed with the polymer solution in the ratio of Vp.:Vg.s = 1: 0.75, where Vp.p is the volume of the polymer solution, m, Vg .s is the volume of the clay-clay suspension, m ³ .

Ready to use when drilling a well, polymer clay or polymer clay has such rheological characteristics:

Density, kg / m ³ 1030-1300

Viscosity, s 25-60

Filtration, cm in 30 min according to MB-6 3.5-4.5

pH 8-9

Thickness of clay peel, mm 0.3-0.5

As can be seen from the above characteristics, the polymer clay drilling mud prepared by the claimed method has good rheological properties, does not require the use of scarce and expensive components for the preparation of drilling mud, its density and other characteristics can be changed over a wide range depending on the cut rocks and open productive strata at equilibrium.

The technical and economic advantage of the invention is as follows.

The prepared polymer clay drilling mud by the claimed method is resistant to the aggressive effects of wellbore salts, bottomhole temperature and pressure and meets the requirements of environmental protection and Gosgortekhnadzor in terms of the magnitude of the created regression of the pressure of the mud column over reservoir pressures when opening productive horizons in combination with a low clay content, helps to preserve them collector properties. It has a high tolerance for drilled rock, ensures trouble-free well drilling, increases penetration by a bit, improves the operation of the downhole motor.

The above positive qualities of the drilling fluid prepared by the claimed method result from its wide field trials during the drilling of oil wells by the drilling enterprises of Almetyevsk and Aznakayevo. Widespread use of the offer at drilling enterprises will provide tangible economic benefits.

Sources of information

1. RF patent No. 2110551, cl. 6 C 09 K 7/04, BI No. 13, 1998

2. RF patent No. 2103313, cl. 6 C 09 K 7/02, BI No. 3, 1998 (the closest analogue).

Claims (1)

A method of preparing a polymer clay drilling mud by mechanically mixing its constituent components: clay, soda ash Na ₂ CO ₃ , a salt-resistant polymer in water, whereby a polymer solution is prepared, then clay is introduced into it, characterized in that Dk is used as a salt-resistant polymer -Drill or PraeStol-2540, as water - industrial water and, in addition, stabilizer-structurant - CMC carboxymethyl cellulose and aluminum sulfate Al ₂ (SO ₄ ) ₃ , a polymer solution is prepared, sequentially introducing Na ₂ CO ₃ into the process water, CMC, the indicated salt-resistant polymer, Al ₂ (SO ₄ ) ₃ , clay is introduced in the form of a suspension dispersed in time with a density of P = 1100-1120 kg / m ³ , weighted with chalk to the required density of P = 1160-1350 kg / m ³ , additionally treated with Na ₂ CO ₃ and CMC, in the ratio V _{s.p .} : V _g.s. = 1: 0.75 - 1: 5, where V _{P. p} - the volume of the polymer solution, m ³ ; V _g.s - the volume of the specified clay suspension, m ³ , in the following ratio of the components of the polymer solution, wt. %: Na ₂ CO ₃ 0.3 - 0.5 CMC 0.25 - 0.35 Specified salt-resistant polymer 0.05 - 0.15 Al ₂ (SO ₄ ) ₃ 0.012 - 0.015 Process water Else