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EP-3712375-B1 - METHOD FOR ELIMINATING FLUID LOSS DURING CONSTRUCTION OF OIL AND GAS WELLS

EP3712375B1EP 3712375 B1EP3712375 B1EP 3712375B1EP-3712375-B1

Inventors

  • SERGEEV, Vitalii Vyacheslavovich

Dates

Publication Date
20260506
Application Date
20181113

Claims (7)

  1. A method for eliminating drilling fluid loss during construction of oil and gas wells, comprising successive pumping a blocking agent and a displacement fluid into a formation, where an emulsion-suspension system is used as the blocking agent and comprises diesel fuel or treated oil from a central processing facility, an emulsifier, a colloidal solution of nanoparticles of silicon dioxide, dry amorphous silicon dioxide, microparticles of ilmenite or trimanganese tetraoxide, an aqueous solution of calcium chloride or potassium chloride; and an aqueous solution of calcium chloride or potassium chloride is used as the displacement fluid.
  2. The method according to Claim 1, characterized in that , in order to eliminate drilling fluid loss in formations with absorption intensity up to 20 m 3 /h, inclusively, an emulsion-suspension system is used as the blocking agent, said system comprising, wt %: - diesel fuel or treated oil from a central processing facility - 15-30, - an emulsifier - 2-3, - a colloidal solution of nanoparticles of silicon dioxide having a particle size from 5 to 100 nm - 0.5-1, - dry amorphous silicon dioxide having a particle size from 5 to 500 nm - 1-3, - ilmenite or trimanganese tetraoxide microparticles having a particle size from 0.2 to 5 µm - 5-10, - an aqueous solution of calcium chloride or potassium chloride - the rest.
  3. The method according to Claim 1, characterized in that , in order to eliminate drilling fluid loss in formations with absorption intensity more than 20 m 3 /h, an emulsion-suspension system is used as the blocking agent, said system comprising, wt %: - diesel fuel or treated oil from a central processing facility - 5-15, - an emulsifier - 2-3, - a colloidal solution of nanoparticles of silicon dioxide having a particle size from 5 to 100 nm - 0.5-1, - dry amorphous silicon dioxide having a particle size from 5 to 500 nm - 3-5, - ilmenite or trimanganese tetraoxide microparticles having a particle size from 0.2 to 5 µm - 5-10, - an aqueous solution of calcium chloride or potassium chloride - the rest.
  4. The method according to Claim 1, characterized in that a composition is used as the colloidal solution of nanoparticles of silicon dioxide, said composition comprising, wt %.: silicon dioxide - 31-32.5 in propylene glycol monomethyl ether - 67-69, water - the rest.
  5. The method according to Claim 1, characterized in that a composition is used as the colloidal solution of nanoparticles of silicon dioxide, said composition comprising, wt %.: silicon dioxide - 30-31 in isopropanol - 67-69, methyl alcohol - the rest.
  6. The method according to Claim 1, characterized in that a composition is used as the colloidal solution of nanoparticles of silicon dioxide, said composition comprising, wt %.: silicon dioxide - 29-31 in ethylene glycol - the rest.
  7. The method according to Claim 1, characterized in that a composition is used as the emulsifier, said composition comprising, wt %: - ethers of higher unsaturated fatty acids, e.g. linoleic, oleic, linolenic acids, and resin acids - 40-42, - amine oxide - 0.7-1, - a high-molecular organic thermostabilizer - 0.5-1, - diesel fuel (summer or winter) - the rest.

Description

The invention relates to the oil-and-gas producing industry, and more particularly to methods for eliminating drilling fluid loss (lost circulation control) during construction of oil and gas wells. One of the most pressing problems in the field of construction of oil and gas wells is absorption of a drilling mud by highly permeable formations and formations having an abnormally low formation pressure (ALFP). Such geological-and-physical features of underground formations lead to complications in an operating procedure, up to a shutdown of a process of well construction. The problem of lost circulation of conventional drilling muds becomes a particularly acute for completion of formations with ALFP. Saline solutions of different densities most widely used in the well construction processes are understood as conventional drilling muds. Elimination of drilling fluid loss in formations with ALFP cannot be effected with conventional water-based drilling muds due to their low viscosity, poor adhesion, lack of plugging capability, and hydrophilization of a rock surface during penetration into producing formations. In order to prevent this kind of troubles, it is necessary to use special technological fluids having relatively low density, increased viscosity and adhesion properties. The main drawbacks of all conventional water-based drilling muds are hydrophilization of rock surfaces, low viscosity, poor adhesion and lack of plugging capability, which result in uncontrollable infiltration of a drilling mud into a drilled-in formation during loss. In this connection, the use of conventional drilling muds is inefficient when formations with abnormal conditions are drilled in. In processes of well construction, while drilling in intervals with abnormal conditions, it is necessary to apply special technological fluids - blocking compositions (blocking agents). Physical and chemical properties of blocking compositions are significantly different from those of conventional drilling muds. An extent of manifestation of the factors that complicate the processes of well construction depends on geological conditions of a deposit and geological-and-physical parameters of formations. The complicating factors are most frequently manifested under following conditions: while drilling wells in areas of formations with a formation pressure lower than a hydrostatic pressure (in these conditions an uncontrollable lost circulation in great volumes takes place which results in hydrophilization of rock surfaces, extension of a well construction period, extra costs and shutdown of the drilling process);while drilling wells in areas of formations with a formation pressure increased relative to hydrostatic pressure (application of heavy water-based drilling muds cannot ensure pressure stabilization in a formation-well system, and hydrophilization of rock surfaces occurs during overbalance). In order to increase efficiency of construction processes of oil and gas wells and solve the task of eliminating complications during drilling in formations with abnormal conditions, it is necessary to apply process fluids having special rheological, surface-active and plugging properties. The document CN104610945 discloses a shutoff oil base drilling fluid comprising a base fluid, an aqueous solution of CaCl2 , emulsifiers, CaO, plugging agents and weighting agents. The document US 2017/292056 discloses invert emulsion drilling fluids. The fluids contain an emulsion comprising hydrophobic silica. A method for preventing and controlling lost circulation in a well is known in the art (USSR Inventor's Certificate No. 1714081, IPC E21B 33/13, E21B 33/138, publication date 23.02.1992), comprising successively injecting an aqueous solution of a polyvalent metal salt and a polymeric plugging material and their subsequent displacement into a lost-circulation formation. A disadvantage of this method is the necessity of saturating an absorbing interval with aqueous solutions of polyvalent metal salts for provoking a subsequent reaction between an aqueous solution and a polymeric material (e.g. a carbamide resin mixture) that is pumped in immediately after. In lost circulation conditions, an aqueous solution of salts, due to its low viscosity, will be completely absorbed by an absorbing interval and infiltrated into the formation. In these conditions, a polymeric material, pumped in immediately after, having viscosity higher than that of the aqueous solution of salts will not mix with the aqueous solution of salts, and, correspondingly, a mixture will not acquire rheological properties required for creating a blocking screen. A method for eliminating fluid loss during drilling and operating wells is known in the art (USSR Inventor's Certificate No. 1810490, IPC E21B 33/138, publication date 23.04.1993), comprising successively injecting diesel and oil alkaline refinery waste, a spacer fluid or a flushing liquid and an aqueous solution of calcium chloride or magne