Union Oil Company of California

David S Pye

Paul W Fischer

Julius P Gallus

LeRoy W Holm

Delbert E Pyle

Robert W Rardin

Donald L Ash

A method for placing a perforated liner in a well penetrating a reservoir containing a high pressure fluid, for example, a geothermal fluid. The holes in one or more sections of a preperforated liner are temporarily closed by inserting therein hollow plugs having an open flange end at the outer surface of the liner and a closed end projecting into the bore of the liner. The lower end of a first section of liner is also closed as with a solid plug. The liner, made up of one or more of the above-described sections which have been joined together, is run into the well through a pressure sealing device at the wellhead, such as a stripper rubber or rotating head. When the liner has been properly positioned in the well, a cutting or scraping tool is run down the inside of the liner to remove the closed end of each plug projecting into the liner, thus opening the perforations in the liner. Reservoir fluids can be produced through the well around the outside of the liner while the liner is being placed.

Method for placing a liner in a pressurized well

A method for conducting foam drilling and workover operations in a bore hole penetrating a subterranean reservoir, particularly a high-temperature reservoir such as a geothermal reservoir, employing an aqueous foaming solution of about 0.08 to 1.0 percent by weight of an amphoteric betaine, about 0.02 to 0.4 percent by weight of a salt of a linear aliphatic or alkyl aryl hydrocarbon sulfonate, and, optionally, from 0.03 to 3.5 percent by weight unneutralized ammonia.

Foam drilling and workover in high temperature wells

A non-damaging variable-density low fluid loss well completion and workover fluid composition which is a dispersion of finely divided slowly oil-soluble, water-insoluble solid particulate matter in a thickened aqueous salt solution. The fluid composition is a mixture of an aqueous solution of a water-soluble inorganic salt, a first high softening point resin fluid loss control additive, a microemulsion fluid loss control additive, and, optionally, a water-dispersible thickening agent and/or a pH control agent. The microemulsion contains water, an oil-soluble surface active agent, a water-dispersible surface active agent, and, as a fluid loss control additive, a mixture of a wax and a second low softening point resin. The microemulsion also optionally contains an additive to prevent phase separation and/or a bactericide. Also disclosed is a method for using this composition in various well drilling, completion and treating operations.

Well completion and workover fluid having low fluid loss

An improved gas drilling method for drilling a well through steam-bearing formations in which emissions of particulate material and other contaminants are reduced by imposing a surface back pressure on, and thereby reducing the velocity of, the contaminant-bearing gas rising through the well. The drilling cuttings and other particulate material rising through the well are subjected to less abrasion and therefore arrive at the surface as larger, more easily separated particles. Drill string erosion is also reduced by the method and the efficiencies of any well effluent treatment facilities are increased.

Method for reducing contaminant emissions in gas drilling operations

A method for conducting foam drilling and workover oprations in a bore hole penetrating a subterranean reservoir employing an aqueous solution of a biodegradable foaming agent composition containing about 0.1 to 1 part by weight of an N-fatty ethyl sulfate salt having the formula: ##STR1## wherein R is a straight chain alkyl radical having from 10 to 16 carbon atoms and M is an alkali metal or ammonium cation, per part per weight of a fatty acid salt having the formula: ##STR2## wherein R.sub.1 is a straight chain alkyl radical having from 9 to 15 carbon atoms and M.sub.1 is an alkali metal or ammonium cation. A particularly preferred foaming agent composition contains sodium 2-(N-lauryl) ethyl sulfate and sodium laurate.

Biodegradable foaming agent in drilling and workover operations

A method for conducting foam drilling and workover operations in a bore hole penetrating a subterranean reservoir employing an aqueous solution of a biodegradable foaming agent composition containing about 0.3 to 3 parts by weight of an N-fatty ethyl sulfonic acid salt having the formula: ##STR1## per part by weight of an N-fatty propionic acid salt having the formula: ##STR2## wherein R and R.sub.1 are straight chain alkyl radicals having from 10 to 16 carbon atoms, and M and M.sub.1 are alkali metal or ammonium cations. A particularly preferred foaming agent composition contains sodium 2-(N-lauryl) ethyl sulfonic acid and sodium 2-(N-lauryl) propionic acid.

Method for foam drilling using a biodegradable foaming agent

A method for drilling a well through a subterranean formation containing one or more zones of unconsolidated dolomite, wherein the drilling operation is interrupted periodically to consolidate the newly drilled incompetent dolomite by the injection of a sequence of reactant slugs comprised of (I) an aqueous solution containing an acid, a surface active agent and a precipitating agent for silicates, (II) an aqueous solution containing a water-soluble silicate, and (III) an aqueous solution containing a precipitating agent for silicates.

Method for drilling a well through unconsolidated dolomite formations

A composition and method for drilling wells through subterranean strata containing high temperature aqueous fluids using a gas-containing aqueous drilling fluid containing an alkaline material to raise the pH of the drilling fluid to provide corrosion protection in the liquid phase and a volatile water-soluble nitrogen-containing compound to provide corrosion protection in the gaseous phase.

Controlling corrosion in gas-containing aqueous drilling fluid

A method of conducting an enhanced oil recovery process in a subterranean reservoir wherein, as part of the process, there is injected into the reservoir as a sweep fluid a foam containing carbon dioxide, water and a foaming agent having the formula: ##STR1## wherein R is a straight chain alkyl radical having from 10 to 16 carbon atoms; and M is an alkali metal or ammonium cation, with sodium being preferred. A particularly preferred foaming agent is sodium lauryl sulfoacetate.

Carbon dioxide foam flooding

Composition and method for drilling a well into a high temperature subterranean reservoir, such as one containing a geothermal fluid, wherein there is used an aqueous foam drilling fluid containing (1) water, (2) gas, (3) a foaming agent, (4) an erosion and corrosion inhibitor, (5) a water-soluble or water-dispersible carboxyalkyl cellulose ether or polyalkylene oxide polymer which both controls the fluid loss of the foam and toughens it, and, optionally, (6) a bit lubricant and/or (7) an anti-torqueing agent.

Composition and method for drilling high temperature reservoirs

A method of conducting foam drilling and workover operations in a bore hole penetrating a subterranean formation, particularly a high-temperature formation such as a geothermal formation, employing an aqueous solution of a foaming agent having the formula: ##STR1## wherein R is a straight chain alkyl radical having from 10 to 16 carton atoms; and M is an alkali metal or ammoniun cation, with sodium being preferred. A particularly preferred foaming agent is sodium lauryl sulfoacetate.

Method of foam drilling using a sulfoacetate foaming agent

A method for reducing the loss of fluid through the walls of a well penetrating a permeable subterranean formation during completion, workover and other operations. The method provides for the use of a fluid comprising an aqueous dispersion of finely divided, slowly oil-soluble, water-insoluble solid particles in an aqueous salt solution containing chrome lignite, hydroxyethyl cellulose and xanthan gum. The density of the fluid is controlled by varying the concentration of salt dissolved in the solution. The finely divided solid particles consist of a homogeneous solid solution of (1) wax; (2) an oil-soluble surface active glyceryl or sorbitan partial ester of a saturated higher fatty acid; and (3) a water-dispersible surface active polyethylene glycol monoester of a saturated higher fatty acid. The particles may optionally include an ethylene/vinyl acetate copolymer, and/or a fatty alcohol.

Method of conducting drilling operations

An oil-soluble, water-insoluble low fluid loss additive composition comprising a particulated, homogeneous solid solution of (1) wax; (2) an oil-soluble polyhydroxy higher fatty acid partial ester surface active agent; and (3) a water-dispersible surface active agent such as a polyoxyethylene alkyl phenol, a polyethylene glycol higher fatty acid ester, a polyoxyethylene polyhydroxy higher fatty acid ester, a polyoxyethylene tertiary fatty amine, or a polyoxyethylene fatty amide condensate. The composition can optionally include small amounts of a polymeric material and/or a higher fatty alcohol. The low fluid loss additive composition can be employed in well drilling, completion and workover operations, and in hydraulic fracturing, acidizing, and other well treating applications.

Low fluid loss additive composition

Well drilling, completion and workover operations, hydraulic fracturing, acidizing, and other well treating operations are improved by the addition to the drilling or treating fluid of an oil-soluble, water-insoluble low fluid loss agent comprising a particulated, homogeneous solid solution of (1) wax; (2) an oil-soluble polyhydroxy higher fatty acid partial ester surface active agent; and (3) a water-dispersible surface active agent such as polyoxyethylene alkyl phenol, a polyethylene glycol higher fatty acid ester, a polyoxyethylene polyhydroxy higher fatty acid ester, a polyoxyethylene tertiary fatty amine, or a polyoxyethylene fatty amide condensate. The agent can optionally include small amounts of a polymeric material and/or a higher fatty alcohol.

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Brea, CA, United States of America

David S Pye