RU2605109C1 - Inhibiting drilling mud - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to oil and gas industry, specifically to water-based drilling muds, and can be used, when drilling oil and gas wells, primarily when drilling unstable clay rocks. Drilling mud includes, wt%: gel powder 2-3; Rosfloc 99M 2-6; as additional clay inhibitor - potassium chloride KCl 3-5; water - balance.

EFFECT: technical effect consists in improved inhibiting properties of mud.

1 cl, 2 tbl

Description

The invention relates to the oil and gas industry, namely to water-based drilling fluids, and can find application in the drilling of oil and gas wells, mainly when drilling unstable clay rocks.

The prior art known cationic drilling fluid (Patent RU 2533478 C1, C09K 8/24, publ. 20.11.2014). Cationic drilling fluid includes, wt.%: Clay powder 5-8; Polydadm 7-15; an additional clay inhibitor - potassium chloride 3-5; water the rest. Known solution has low inhibitory properties.

The closest technical solution to the proposed one is an inhibitory drilling fluid, including wt.%: High-colloidal bentopowder grade PBMV 6-15, water-soluble polymer - cationic coagulant Rosflock brand 99M 2-6, water - the rest (Patent RU 2468057 C2, C09K 8/24, publ. 11/27/2012). A disadvantage of the known composition is the low inhibitory properties of the solution.

The problem solved by the invention is to create a drilling fluid that meets the specified requirements.

The technical result to which this invention is directed is to increase the inhibitory properties of the solution.

This technical result is achieved due to the fact that in the composition of the drilling fluid, including water, clay powder and Rosflock 99M, potassium chloride KCl was introduced as an additional clay inhibitor in the following ratio, wt.%:

Clay powder 2-3; Rosflock 99M 2-6; Kcl 3-5; Water Rest

To obtain an additional technical result, increase the density, the drilling fluid is weighted with barite concentrate.

Various brands can be used as clay powder. The optimum concentration of clay powder depends on its brand. As the grade of clay powder worsens, the concentration increases, and with an increase in quality, the concentration decreases. Brand, i.e. the grade of clay powder, in the proposed composition, does not significantly affect the technological parameters of the solution, but characterizes its consumption. In the proposed drilling fluid can be used bentonite clay powder of any of the grades PBMA, PBMB, PBMV, PBMG and PKGN, which is produced in accordance with TU 2164-004-0013836-2006 "Clay powder". The research results are shown in tables taking into account the use of PBMA grade clay powder in the composition of the proposed solution.

Rosflock 99M is a cationized low molecular weight polyacrylamide with linear-cyclic functional groups. The structural formula of Rosflock 99M is presented from repeating monomer units.

In a marketable product, the molecular weight of Rosflock 99M may vary from 0.5 · 10 ⁶ to 1.5 · 10 ⁶ . Rosflock 99M is available in accordance with TU 2482-001-22361394-2001 in dry and liquid form of various concentrations.

The invention is illustrated in Tables 1-2. Table 1 shows the results of studies on the effect of KCl on the technological parameters of drilling fluids with Rosflock 99M content. In tables 1-2, the following notation and abbreviations are accepted: GP - PBMV grade clay powder; PF - an indicator of a filtration; η _square - plastic viscosity; τ ₀ - dynamic shear stress; СНС1 / 10 - static shear stress for 1 and 10 minutes, respectively.

During drilling in clay deposits, the clay enriches the clay phase and increases the structural and rheological parameters η _pl. , τ ₀ , SNA. From Table 1 (p. 6) it can be seen that the increase in the structural and rheological parameters of the proposed solution with the introduction of 15% clay sludge does not exceed permissible values, which indicates an improvement in the inhibitory properties of the proposed solution compared to the solution known from the prior art (Table 1, p . one).

Further, the inhibitory properties of the solution were evaluated by impregnating the liquid into plastic clay samples in the test medium. Moreover, the relative increase in mass in% is defined as:

Δm = (m ₂ -m ₁ ) 100% / m ₁ ,

where m ₂ is the mass of the sample aged 7 days in the test medium;

m ₁ is the mass of the original sample.

Table 2 reflects the results of studies to enhance the inhibitory properties of the solution. From Table 2 it follows that when the KCl content is below 3%, the inhibitory properties of the solution deteriorate (Table 2, p. 1). Hence, the minimum permissible KCl content is 3% (Table 2, p. 3). An increase in KCl content of more than 5% is ineffective (Table 2, p. 5), since it leads to overuse of KCl, with a slight increase in the inhibitory properties of the solution.

Thus, according to the results of the studies shown in Table 2, it can be seen that the use of Rosflock 99M and KCl in the indicated amounts can improve the inhibitory properties of the solution.

An increase in the density of the drilling fluid is made by the addition of barite. The proposed drilling fluid has a high resistance to salt aggression: the addition of calcium chloride, sodium practically does not affect the technological parameters of the system.

Prepare a solution as follows. First you need to mix the water with the clay powder before it dissolves, then add the Rosflock 99M to the clay suspension and after KCl and, if necessary, a barite weighting agent.

Claims (1)

Drilling mud, including water, clay powder and Rosflock 99M, characterized in that as an additional clay inhibitor, potassium chloride KCl is used in the following ratio of components, wt.%:
Clay powder 2-3 Rosflock 99M 2-6 Kcl 3-5 Water Rest