RU2374292C2 - Inhibiting drill fluid - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to construction of oil and gas wells, specifically to water-based drill fluids for drilling wells. The inhibiting drill fluid contains, wt %: polyglycol 8 to 12; bentonite 2 to 3; reagent-stabiliser 0.4 to 0.9; lubricant additive 1 to 2; floatation reagent 1 to 1.5; anti-foaming agent 0.01 to 0.02; water 80 to 86; carbonate filling material - the rest, until specified density of the said solution.

EFFECT: improved inhibiting properties of drill fluid.

1 ex

Description

The invention relates to the field of construction of oil and gas wells, in particular to water-based drilling fluids for drilling and completion. Known drilling fluid (1) for drilling in crumbling rocks, containing clay, polyglycol, a stabilizing reagent, potassium chloride, water glass and water.

The disadvantages of this silicate-clay solution are:

1) relatively low inhibitory properties, evaluated by the rate of wetting of clay material;

2) the inefficiency of the use of silicate solutions for opening productive formations, expressed in low values of the recovery coefficient of the initial permeability when they are filtered through cores;

3) the absence of the ability of the filtrate of this solution to hydrophobize the porous medium of the reservoir.

Known drilling fluid (2) containing clay, polyglycol, a stabilizing reagent, potassium chloride, a lubricant additive DSB-4TT and water. This solution is promising for opening productive formations, since it has a hydrophobic ability, but it has insufficient high inhibitory properties and low electrical resistivity due to the presence of KCl in the composition.

The closest technical solution to the claimed invention is a drilling fluid (3) for drilling in crumbling rocks and opening productive formations containing clay, a stabilizing reagent, polyglycol, an inhibitory additive and water. The disadvantages of this solution are:

1. The hazard class of certain reagents (for example PKD-515, Sonbur 1101) does not allow the use of this solution in offshore drilling.

2. The carbonate weighting agent used by Soda OJSC is a technical product that is heterogeneous in disperse composition, which negatively affects the quality of the filtering of the crust and the sedimentation stability of the solution.

3. The low polyglycol content does not provide the inhibitory effect required when drilling in rock-hazardous rocks.

The task of the invention is to increase the inhibitory properties of the drilling fluid.

The problem is solved in that the drilling fluid containing polyglycol, bentonite, a stabilizing reagent, a lubricating additive, a carbonate weighting agent and water, additionally contains flotation reagent and antifoam, in the following ratio of ingredients, wt.%: Polyglycol 8-12; bentonite 2-3; stabilizer reagent 0.4-0.9; lubricating additive 1-2; flotation reagent 1-1.5; antifoam 0.01-0.02; water 80-86; carbonate weighting agent the rest, up to the design density of the specified solution.

They use: antifoam agent - Penta-465, PES-1 and others similar to them; bentonite grades PMBA and PMBV; PAC-based stabilizer reagent (polyanionic cellulose) - Aqua FLO-HV, Aqua FLO-LV, PACU-LV; flotation reagent T-92, T-66, T-800; FK-2000 lubricant, glital or lubricant; carbonate weighting agent - marble chips, limestone chips or siderite chips.

An example of a drilling fluid preparation. The drilling fluid preparation tank equipped with a paddle mixer is filled with technical (or sea) water of 80 wt.%. Penta-465 antifoam is introduced in an amount of 0.01 wt.%, Then polyglycol is introduced with constant stirring at the rate of 12 wt.%. PMBA grade bentonite is introduced through an injection funnel in an amount of 3 wt.%. The PAC-based stabilizer reagent, Aqua FLO-HV, is poured in an amount of 0.5 wt.% And stirred for 2 hours. Then the flotation reagent T-92 is poured in the amount of 1 wt.%. A lubricating additive for drilling fluids FC-2000 is introduced in an amount of 1.5 wt.% And a carbonate weighting agent in the form of marble chips in an amount of 1.99 wt.% Until the design density of the specified solution is 1120 kg / m ³ . The solution is considered ready.

The use of the declared drilling fluid provides the necessary period of steady state of rock-hazardous mudstones and clays, reduces the production of sludge and increases the efficiency of mechanical cleaning agents. Optimum conditions are created for maintaining particles of the solid phase in suspension and for cleaning the well, including from a horizontal section of the wellbore. The use of polyglycol as an inhibitor provides the necessary values of the resistivity of the drilling fluid, which favorably affects the quality of electric logging. Bentonite with a high yield of solution is introduced to give the claimed solution optimal parameters, viscosity and structural-mechanical properties that prevent the precipitation of a carbonate weighting agent from the solution. The flotation reagent T-92 of complex action is introduced to improve the lubricating properties that improve the removal of cuttings to the surface, and is a hydrocarbon neutralizer. As the stabilizing reagent in the inventive solution, cellulose-based reagents are used that maintain low fluid loss of the solution, reduce the coefficient of friction of the clay crust and withstand calcium chloride aggression.

Information sources

1. RF patent No. 2132351 IPC S09K 7/02.

2. RF patent No. 2174996 IPC S09K 7/02.

3. RF patent №2242492 IPC С09К 7/02.

Claims (1)

An inhibitory drilling fluid containing polyglycol, bentonite, a stabilizing reagent, a lubricating additive, a carbonate weighting agent and water, characterized in that it additionally contains flotation reagent and antifoam in the following ratio, wt.%:
Polyglycol 8-12 Bentonite 2-3 Reagent stabilizer 0.4-0.9 Lubricant additive 1-2 Flotoreagent 1-1.5 Anti-foaming agent 0.01-0.02 Water 80-86 Carbonate weighting compound rest,
to the design density of the specified solution.