SU1615170A1 - Drilling mud for lost circulation formations - Google Patents

Abstract

The invention relates to the drilling of oil and gas wells in absorbing formations. The goal is to increase the stability of the filtration and structural properties of the solution at pressures up to 19 MPa due to the use of the fly ash product as a lightening additive. The solution contains the following ingredients when their ratio, wt.%: Bentonite 4-6, the product of flotation of fly ash 10-30, water - the rest. The solution is prepared by mixing the prehydrated for 1 day. bentonite with water to obtain a homogeneous suspension and the subsequent introduction into the suspension of the product of flotation of fly ash and mixing. The solution has a density of 860–960 kg / m ³ and stable structural and filtration parameters, preventing complications associated with pipe sticking. 1 tab.

Description

The invention relates to the drilling of wells in the oil and gas industry. and geological exploration industry, and is intended for drilling in absorbing reservoirs.

The purpose of the invention is to increase the stability of the filtration and structural properties of the drilling fluid at pressures up to 19 MPa.

The drilling fluid contains bentonite, water and as a facilitating additive - the product of the float of fly ash in the following ratio of ingredients, wt.%:

Bentonite4-6

The product of flotation of fly ash 10-30 2odaEstal

The product of the floatation of fly ash is a non-utilizable waste product from the power plant. It is released during the non-reactant flotation of fly ash formed as a result of burning coal and subsequent separation of the ash pond in the aquatic environment. .Pro; the fly ash float is an untraceable gray powder, which is a sphe-

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It has a size of 20 to 200 µm, and has the following composition,%: SiO, 53.8, - A12.0, 30.6; , 2; MgO 1.6; CaO 0.8; K ,, 0 6.2; 1.1; ti02 0.9; other impurities, the rest. Bulk density 415 kg / m

Product particles, such flotation, are hollow spheres with an average diameter of about 100 microns. The density of particles of the flotation product is 400–600 kg / m, and the particles of fly ash are 2100– 2300 kg / m3.

Due to density differences, hollow microspheres can be made of fly ash by flotation. The content of hollow microspheres in ash and ash is on the order of 5–6% by volume.

Spherical formations of the fly ash flotation product are destroyed at a pressure of 19 MPa, which is confirmed by the results of experimental works, performed in a CC-3 consistometer. For example, 50 g of bentonite is introduced into 200 g of water, stirred for 5 minutes and kept at rest for a day for hydration. To the resulting paste of pre-hydrated bentonite, 500 g of water is added, stirred until a homogeneous suspension is obtained, and then 200 g of the product of the fly ash is introduced into the paste and mixed again for 15 minutes.

The resulting solution has the following composition, wt.%: Bentonite 5; product ash flotation float 20; water 75. n has the following parameters: density 900 kg / m, nominal viscosity 40 s, water loss 16 cm, static shear stress through

1 and 10 min respectively 21 and

38 dPa, stability 20 kg / m3, pH 7.2. The drilling fluid is placed in consistometer KC-3. After mixing in a consistometer at a pressure of 15 MPa for 2 hours, the consistency of the drilling fluid does not change. After mixing in a consistometer for

2h at pressures of 16, 17, and

18 MPa drilling fluid consistency is unchanged. After mixing in a consistometer for 6 minutes at a pressure of 19 MPa, the consistency of the drilling mud rises to 22 sr. units, which is accompanied by the partial destruction of the spherical formations of the fly ash product flotation;

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five

40

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It is also known that the hydrostatic strength of spherical formations from the product of flotation of fly ash at a 50% level of destruction is about 25 MPa.

To assess the technological properties of the drilling fluid, characteristics are measured using conventional techniques and devices. Density (p) is measured by the pycnometric method, conditional viscosity (HC) using a VBR-1 funnel, water loss (B) using a VM-6 device, static shear stress after 1 and 10 minutes () - VSN -3, .РН - on the device pH-340, stability (Hg) - in the cylinder CS-2.

Example 1. In 200 g of water, 30 g of bentonite are introduced, stirred for 5 minutes and kept at rest for a day for hydration. To the resulting paste of prehydrated bentonite, 670 g of water are added, stirred for 15 minutes to obtain a homogeneous suspension, and then 100 g of flotation product of float glue are obtained and mixed again for 15 minutes. The resulting drilling fluid has a composition, wt.%: Bentonite 3, the product of the flotation of fly ash 10 water 87. It has the following properties: About 950 kg / m, HC 25 s; H 20 cm, SNS / s 18/16 dPa; P. 80 kg / m; pH 7.1.

Example 2. In 200 g of water, 40 g of bentonite are introduced, stirred for 5 minutes and quenched at rest for a day for hydration. To the resulting paste of pre-hydrated bentonite, 710 g of water is added, stirred for 15 minutes until a uniform suspension is obtained, and then 50 g of the product of the fly ash are added to the mixture and mixed again for 15 minutes. The resulting drilling mud has the composition, wt.%: Bentonite 4, the product of flotation of fly ash 5j water 91. It has the following properties: O -1010 .kg / m;: HC 25 s; H 20 cm, CHC / 6/12 dPa; 0 0 kg / mM, 1.

Example 3. In 200 g of water, 50 g of bentonite are introduced, stirred for 5 minutes, and kept at rest for a day for hydration. To the resulting paste of pre-hydrated bentonite, add 550 tons of water.

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mix for 15 minutes until a uniform suspension is obtained, and then 20 g of the product of the fly ash flotation is introduced and stirred for 15 minutes. The resulting drilling fluid has a composition, wt.%: Bentonite 5; the product of flotation of fly ash 20, water 75. It has the following properties: p 900 kg / m J s, B 16 cm, СНС / hell 21/38 dPa, P. .. 20 kg / мз., pH 7.2, К 1.7 mm.

The table shows the technological parameters of drilling fluids containing a different amount of lightening additive - the product of flotation of fly ash.

In contrast to the plasmilon-containing drilling mud, the proposed drilling fluid has a high stability, which is 20 kg / m3, and a small filter thickness.

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the technological properties of the drilling fluid and prevents complications associated with sticking the drill pipe by reducing the thickness of the filter cake while maintaining a low density.

Claims (1)

Invention Formula Drilling borehole in absorbing formations, including bentonite, water and facilitating the additive, characterized in that, in order to improve the stability of the filtration and structural properties of the drilling fluid at pressures up to 19 MPa, it contains as a lightweight additive flotation ash the ratio of ingredients, wt.%: Bentonite4-6 Flotation product