Baker Hughes Corporation

Milchem Incorporated

Dorothy P Enright

Alphonse C Perricone

James M Lucas

Pierre E Collee

Dennis K Clapper

William M Dye

F Martin Smith

Steven R Radford

William A Mallow

A method for protecting integrity of a core sample during transport from a subterranean formation to the surface comprising: cutting a core sample from the subterranean formation using a drilling fluid; encapsulating the core sample with an encapsulating material that is separate from the drilling fluid and comprises a property which renders the encapsulating material capable of protecting the chemical integrity of the core sample during transport from the subterranean formation to the surface, wherein the property is other than a property selected from the group consisting of a viscosity which increases in response to a decrease in temperature and an ability to solidify in response to a decrease in temperature; and, transporting the encapsulated core sample from the subterranean formation to the surface.

Method for preserving core sample integrity

The present invention provides a method for protecting the integrity of a core sample during transport from a subterranean formation to the surface comprising: cutting a core sample from the subterranean formation using a drilling fluid; encapsulating the core sample with an encapsulating material separate from the drilling fluid, the encapsulating material being capable in the absence of a chemical reaction of protecting core sample integrity during transport from said subterranean formation to said surface; and, transporting the encapsulated core sample from the subterranean formation to the surface.

The present invention provides a method for maximizing the chemical integrity and, if desired, maintaining the mechanical integrity of a core sample during transport from a subterranean formation to the surface. The method involves cutting and encapsulating the core sample as it enters the core barrel with an encapsulating material that either (a) inherently is capable of protecting the chemical integrity of the core sample, or (b) is capable of increasing in viscosity and/or solidifying in response to natural decreases in temperature to maintain the mechanical integrity and maximize the chemical integrity of the core sample during transport.

Method and composition for preserving core sample integrity using an

The present invention provides a method and composition for encapsulating a core sample as it enters a core barrel with a water-based encapsulating material that preferably comprises an expandable lattice type clay. The water-base causes the expandable lattice type clay to swell, forming a plastic mass which can be pumped into a core barrel to encapsulate the core sample and maintain the chemical and mechanical integrity of the sample during transport to the surface. Filtration control agents preferably are added to the encapsulating material to prevent water from penetrating into or interacting with the core. These control agents prevent the loss and/or invasion of water or other gaseous or fluid components. The control agents are (a) a water soluble thickening agent, and, (b) a particulate sealing agent capable of (i) sealing the pores of the core sample, or (ii) bridging the pores of the core sample and permitting the thickening agent to adsorb to the bridge to seal the pores. The integrity of the core sample will be maximized if a pressure core barrel is used to transport the encapsulated core sample to the surface.

Method and composition for preserving core sample integrity using a

A method is provided for the prevention of balling of formation cuttings upon the surface of drilling equipment and for lubrication of said equipment used in conjunction with subterranean well operations. An aqueous system is prepared to which is added a composition of a water insoluble polyglycol having a molecular weight of from between about 1,200 and about 10,000, an emulsifying surfactant having a hydrophilic/hydrophobic balance of about 4 or more, and a hydrotrope. An additive for use in the method also is disclosed.

Drilling fluid methods and composition

The present invention provides a modified liquid phase drilling fluid having desirable properties of shale swelling inhibition, lubrication, and high temperature performance. The fluid does not rely on the incorporation of inorganic salts or high molecular weight water soluble polymers for control of shale swelling or shale disintegration and exhibits performance characteristics, approaching those of oil base drilling fluids, without the objectionable properties of hydrocarbon oils or its potential hazardous impact on the environment. The fluid is comprised of the following: (1) a liquid phase containing; (a) a water phase comprising fresh water, seawater, brine, simulated brine, or mixtures thereof; and (b) a water-soluble component selected from the class consisting of polyhydric alcohols, glycol, glycol ethers, polypropylene glycols, polyethylene glycols, ethylene oxide-propylene oxide copolymers ('EO-PO'), alcohol-initiated EO-PO copolymers and/or mixtures thereof, the ratio of said water-soluble component in the total liquid phase being from about 5% to about 50% by volume; (2) a viscosifier for suspension of solids in said liquid phase; and (3) a filtration control agent. The fluid with the water soluble component will exhibit a lubricity coefficient lower than that for substantially the same fluid without the water soluble component as determined by the American Petroleum Institute's 'Procedure for Determination of Lubricity Coefficient (Tentative)' (1980), and the linear swelling on a reconstituted 'gumbo' shale inserted for about 60 minutes of said drilling fluid being from lower than that for substantially the same fluid without the water soluble component, as measured by the 'Swelling Test', 'Rigsite Shale Evaluation Techniques for Control of Shale-related Wellbore Instability Problems', SPE/IADC Paper No. 16054, pages 52-53, (1987).

Modified non-polluting liquid phase shale swelling inhibition drilling

The present invention provides a modified liquid phase drilling fluid having desirable properties of shale swelling inhibition, lubrication, and high temperature performance. The fluid does not rely on the incorporation of inorganic salts or high molecular weight water soluble polymers for control of shale swelling or shale disintegration and exhibits performance characteristics, approaching those of oil base drilling fluids, without the objectionable properties of hydrocarbon oils or its potential hazardous impact on the environment. The fluid is comprised of the following: (1) a liquid phase containing: (a) a water phase comprising fresh water, seawater, brine, simulated brine, or mixtures thereof; and (b) a water-soluble component selected from the class consisting of polyhydric alcohols, glycol, glycol ethers, polypropylene glycols, polyethylene glycols, ethylene oxide-propylene oxide copolymers ('EO-PO'), alcohol-initiated EO-PO copolymers and/or mixtures thereof, the ratio of said water-soluble component in the total liquid phase being from about 5% to about 50% by volume; (2) a viscosifier for suspension of solids in said liquid phase; and (3) a filtration control agent. The fluid with the water soluble component will exhibit a lubricity coefficient lower than that for substantially the same fluid without the water soluble component as determined by the American Petroleum Institute's 'Procedure for Determination of Lubricity Coefficient (Tentative)' (1980), and the linear swelling on a reconstituted 'gumbo' shale inserted for about 60 minutes of said drilling fluid being from lower than that for substantially the same fluid without the water soluble component, as measured by the 'Swelling Test', 'Rigsite Shale Evaluation Techniques for Control of Shale-related Wellbore Instability Problems', SPE/IADC Paper No. 16054, pages 52-53, (1987).

The present invention provides a modified liquid phase drilling fluid having desirable properties of shale swelling inhibition, lubrication, and high temperature performance. The fluid is comprised of the following: (1) a liquid phase containing: (a) a water phase comprising fresh water, seawater, brine, simulated brine, or mixtures thereof; and (b) a water-soluble component selected from the class consisting of polyhydric alcohols, glycol, glycol ethers, polypropylene glycols, polyethylene glycols, ethylene oxide-propylene oxide copolymers ('EO-PO'), alcohol-initiated EO-PO copolymers and/or mixtures thereof, the ratio of said water-soluble component in the total liquid phase being from about 5% to about 50% by volume; (2) a viscosifier for suspension of solids in said liquid phase; and (3) a filtration control agent.

The invention relates to an aqueous solution of a filtration control agent for utilization in said aqueous drilling fluid, useful in a method of forming a filter cake on the wall of a well for the reduction of filtrate from said drilling fluid, which is effective at high temperatures and pressures, the terpolymer consisting essentially of: (1) an alkali metal acrylate units; (2) hydroxyalkyl acrylate units; and (3) acrylamide.

Aqueous drilling fluid additive

The invention relates to an aqueous drilling fluid composition, a filtration control agent for utilization in said aqueous drilling fluid, and a method of forming a filter cake on the wall of a well for the reduction of filtrate from said drilling fluid, by utilization of a copolymer of: (1) a (meth) acrylamido alkyl sulfonic acid or alkali metal salt thereof; and (2) a (meth) acrylamide or N-alkyl (meth) acrylamide. The copolymer may be cross-linked with a quaternary ammonium salt cross-linking agent.

Drilling fluid containing a copolymer filtration control agent

The invention relates to an aqueous drilling fluid composition, a filtration control agent for utilization in said aqueous drilling fluid, and a method of forming a filter cake on the wall of a well for the reduction of filtrate from said drilling fluid, which are effective at high temperatures and pressures, by utilization of a terpolymer of: (1) a monovalent alkali metal salt of acrylic acid; (2) an hydroxy alkyl acrylate; and (3) acrylamide.

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Houston, TX, United States of America

Dorothy P Enright