CN-121991653-A - Collapse-proof and leakage-proof drilling fluid for improving bearing capacity of weak stratum and preparation method thereof

CN121991653ACN 121991653 ACN121991653 ACN 121991653ACN-121991653-A

Abstract

The invention relates to an anti-collapse and anti-leakage drilling fluid for improving the bearing capacity of a weak stratum and a preparation method thereof, wherein the anti-collapse and anti-leakage drilling fluid comprises 3-5% of bentonite, 0.1-0.3% of sodium carbonate, 0.2-0.4% of caustic soda, 0.2-0.4% of calcium oxide, 0.5-1% of vinyl monomer multipolymer MAN101 for the drilling fluid, 0.5-1% of vinyl monomer multipolymer MAN104 for the drilling fluid, 0.4-0.6% of compound ammonium salt, 1-3% of filtrate reducer, 4-8% of anti-collapse inhibitor, 2-4% of superfine calcium carbonate, 1-3% of emulsified asphalt, 1-3% of plugging agent QCX, 0.4-0.6% of liquid lubricant and the balance of water. The invention can form a compact filter cake, and reduce the permeability of the filter cake to 10 ‑6 mD or even 10 ‑7 mD, so that the filtration loss of drilling fluid can be effectively reduced. The invention can prevent the transmission of pressure and prolong the pressure break-through time to 200 hours, thereby preventing the well wall from collapsing. The invention can also improve the bearing capacity of the rock by more than 10MPa.

Inventors

YIN ZEBIN
YAO XUYANG
LIU KECHENG
Xing Linzhuang
REN TAO
HUANG HONG
YE CHENG
CHEN HAO
LU TIEMEI

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241107

Claims (9)

1. The collapse-preventing and leakage-preventing drilling fluid for improving the bearing capacity of the weak stratum is characterized by comprising the following components in percentage by mass: The balance being water.
2. The collapse and leakage prevention drilling fluid for improving the bearing capacity of a weak stratum according to claim 1, wherein the collapse and leakage prevention drilling fluid further comprises a weighting agent, and the dosage of the weighting agent is determined according to the density of the drilling fluid.
3. The collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum according to claim 2, wherein the weighting agent comprises one or more of iron ore powder, activated iron ore powder, manganese ore powder, calcium carbonate, barium carbonate and square lead ore powder.
4. The collapse and leakage prevention drilling fluid for improving the bearing capacity of a weak stratum according to claim 1, wherein the compound ammonium salt is prepared by compounding hydrolyzed polyacrylate ammonium salt NH 4 -HPAN and polyacrylamide PAM in a ratio of 1:1.
5. The collapse and leakage preventing drilling fluid for improving the bearing capacity of the weak stratum according to claim 1 or 2, wherein the filtrate reducer is filtrate reducer HY-2 for the drilling fluid; The collapse prevention inhibitor is KCl; The liquid lubricant is liquid lubricant HLG.
6. The collapse and leakage prevention drilling fluid for improving the bearing capacity of a weak stratum according to claim 1, wherein the particle size of the superfine calcium carbonate is 0.075-0.15 mm.
7. The collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum according to claim 1, wherein the plugging agent QCX is calcium carbonate with the particle size of 0.5-1.5 mm.
8. The collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum according to claim 5, wherein the collapse and leakage prevention drilling fluid comprises, by mass, 4% of bentonite, 0.2% of sodium carbonate, 0.3% of caustic soda, 0.3% of calcium oxide, 0.5% of a vinyl monomer multipolymer MAN101 for the drilling fluid, 0.5% of a vinyl monomer multipolymer MAN104 for the drilling fluid, 0.5% of a compound ammonium salt, 1.5% of a filtrate reducer HY-2 for the drilling fluid, 5% of an collapse inhibitor KCl, 3% of superfine calcium carbonate, 2% of emulsified asphalt, 1.5% of a plugging agent QCX, 0.5% of a liquid lubricant and a certain amount of barite.
9. The preparation method of the collapse-preventing and leakage-preventing drilling fluid for improving the bearing capacity of the weak stratum is characterized by comprising the following steps of: S1, preparing base slurry Adding 3-5% of bentonite, 0.1-0.3% of sodium carbonate, 0.2-0.4% of caustic soda and 0.2-0.4% of calcium oxide into a certain amount of water, uniformly stirring, and preparing base slurry; S2, preparing anti-collapse and anti-leakage drilling fluid The method comprises the steps of adding, by mass, 0.5% -1% of a vinyl monomer multipolymer MAN101 for drilling fluid, 0.5% -1% of a vinyl monomer multipolymer MAN104 for drilling fluid, 0.4% -0.6% of a compound ammonium salt, 1% -3% of a filtrate reducer for drilling fluid, 4% -8% of a collapse inhibitor, 2% -4% of superfine calcium carbonate, 1% -3% of emulsified asphalt, 1% -3% of a plugging agent QCX, 0.4% -0.6% of a liquid lubricant and a certain amount of barite into base slurry, and uniformly stirring to obtain the collapse-preventing and leakage-preventing drilling fluid capable of improving the pressure bearing capacity of weak stratum.

Description

Collapse-proof and leakage-proof drilling fluid for improving bearing capacity of weak stratum and preparation method thereof Technical Field The invention belongs to the technical field of oilfield chemical additives, and particularly relates to collapse and leakage prevention drilling fluid for improving the bearing capacity of a weak stratum and a preparation method thereof. Background The drilled exploration well data show that the coal seam in partial areas is developed, the coal seam is strong in brittleness, the effective stress for damaging the coal seam is low, and accordingly the complex conditions of well wall instability and well leakage are easy to occur. Factors such as improper operation or collision of drilling tools are easy to induce the coal seam to form cracks or enable the connectivity of the original cracks of the coal seam to be better, and the lost circulation problem is more prominent. The invention patent of CN116004200A discloses an oil-based drilling fluid for improving the bearing capacity of stratum, and a preparation method and application thereof. The drilling fluid comprises 20 parts by weight of CaCl 2 brine, 4 parts by weight of organic soil, 3-5 parts by weight of emulsifier, 2-5 parts by weight of high-temperature-resistant salt-resistant filtrate reducer, 2-4 parts by weight of alkalinity regulator and 3-9 parts by weight of inorganic micro-nano rigid particles based on 80 parts by weight of white oil. However, the drilling fluid provided by the invention lacks an inhibitor, has poor inhibition performance, and is not suitable for improving the pressure bearing capacity of weak formations such as coal beds. The invention patent of CN112143469A discloses a drilling fluid for improving the bearing capacity of stratum, a preparation method and application thereof. The drilling fluid comprises, by weight, 2-9 parts of bentonite, 0.1-1 part of low-viscosity polyanion cellulose, 1-5 parts of lignite resin, 0.1-2 parts of high-temperature and salt-resistant filtrate reducer, 0.1-2 parts of silanol inhibitor, 0.5-5 parts of inorganic micro-nano rigid particles and 1-10 parts of emulsified asphalt based on 100 parts of water. However, the drilling fluid provided by the invention lacks an inhibitor, has poor inhibition performance, and is not suitable for improving the pressure bearing capacity of weak formations such as coal beds. The invention patent of CN104046338A discloses an anti-collapse and anti-leakage drilling fluid and a construction method thereof, which are suitable for middle-life tri-stack stratum with low bearing capacity, repeated block leakage and high plugging difficulty. The drilling fluid consists of polyanionic cellulose, a drilling fluid salt-resistant filtrate reducer, water-dispersible emulsified asphalt powder, superfine calcium carbonate, sodium formate, sodium hydroxide, potassium chloride and clear water. However, the drilling fluid disclosed by the invention contains less plugging agent, does not contain plugging agent with the particle size exceeding 1mm, and is not suitable for stratum with larger seam width. Disclosure of Invention Based on the problems existing in the prior art, the invention aims at providing the collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum, and also aims at providing a preparation method of the collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum, and the application of the collapse and leakage prevention drilling fluid for improving the bearing capacity of the weak stratum. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: the collapse-preventing and leakage-preventing drilling fluid for improving the bearing capacity of the weak stratum comprises the following components in percentage by mass: As a further optimization of the invention, the collapse and leakage prevention drilling fluid further comprises a weighting agent, wherein the dosage of the weighting agent is determined according to the density of the drilling fluid. As a further preferable scheme of the invention, the weighting agent comprises one or more of iron ore powder, activated iron ore powder, manganese ore powder, calcium carbonate, barium carbonate and lead ore powder. As a further preferable scheme of the invention, the compound ammonium salt is prepared by compounding hydrolyzed polyacrylamine ammonium salt NH4-HPAN for drilling fluid and polyacrylamide PAM according to a ratio of 1:1. As a further preferable scheme of the invention, the filtrate reducer is filtrate reducer HY-2 for drilling fluid, the collapse prevention inhibitor is KCl, and the liquid lubricant is liquid lubricant HLG. As a further preferable scheme of the invention, the particle size of the superfine calcium carbonate is 0.075-0.15 mm. The plugging agent QCX is calcium carbonate with the particle size of 0.5-1.5 mm. As a specific p