Atlantic Richfield Company

Schlumberger Technology Corporation

Dowell Schlumberger Incorporated

Joseph H Schmidt

James C Abel

Keith R Ferguson

Curtis G Blount

Michael L Bill

Donald F Scheve

Dennis R Reimers

Thomas K Perkins

Frank E Bergren, Iii

Lamar L Gantt

John A Emerson

Ahmed S Abou-Sayed

Andrew J Bond

Philip L Stanton

Roger F Keese

Ching H Yew

Robert A Benham

Jerry L Brock

Karl W Schuler

William H Smalstig

Michael J Bolkovatz

Charles R Eason, Jr

J Lawrence Bacak

Weakly consolidated hydrocarbon fluid bearing earth formation zones having a cohesive strength of about 500 psi or less are produced by completing a well penetrating the zone and initiating production of solids laden fluid from the zone through the well to generate a near wellbore cavity. Production of solids laden fluid is continued until the cavity grows to a point wherein the fluid velocity across the cavity face decreases to a value below the solids particulate transport velocity wherein continued production of fluid will result in a very low or negligible rate of production of solids particulates. Solids particulates are separated from the produced mixture at the surface, the solids are treated to reduce the particle size and reinjected in a slurry into a disposal well for disposal in a hydraulically fractured or disaggregated formation zone remote from the production zone. Cavity growth and production may be carried out by throttling a free flowing well or by artificial lift, preferably utilizing power fluid and a hydraulic jet pump or gas lift techniques.

Well completions in weakly consolidated formations

Fractures are initiated or extended into fluid producing earth formations from a well by providing a reservoir of high pressure gas at the earth's surface together with a flow control valve or a frangible closure, such as a shear disk, interposed in a conduit connecting the reservoir to the well. The well is precharged with high pressure gas at a pressure less than or about the same as the reservoir gas pressure. Fracture initiation and/or extension may be carried out by firing the perforation gun and opening the flow control valve between the reservoir and the wellhead in timed relation or by allowing a pressure drop across a shear disk interposed between the reservoir and the wellhead to effect rupture of the shear disk to release the reservoir charge. In wells where perforations are already formed, a shear disk or other frangible closure in the well tubing may be ruptured to release a precharge of high pressure gas in the tubing string to begin fracture formation or extension followed by flow of high pressure gas discharged from the reservoir to continue the fracture initiation or extension.

Over-pressured well fracturing with surface reservoir and actuator system

Perforations and other openings in well casings, liners and other conduits may be substantially blocked or sealed to prevent fluid flow between the casing or liner interior and an earth formation by placing a radially expansible sleeve adjacent the perforations or openings and urging the sleeve into forcible engagement with the casing or inner wall using an explosive charge. An apparatus including a radially contracted sleeve formed by a coiled plate member or a tubular member having flutes defined by external and internal folds, may be deployed into a well casing or liner through a production or injection tubing string and on the end of a flexible cable or coilable tubing. An explosive charge disposed on the apparatus and within the sleeve may be detonated to urge the sleeve into forcible engagement with the casing inner wall.

Apparatus and method for sealing perforated well casing

Perforations and cracks in wellbore liners or casings may be temporarily or permanently covered by a radially-expansible, coiled sleeve member formed by a sheet of elastically-deflectable material such as stainless steel which is coiled and placed in a cylinder which may be conveyed into a well to a working position for deployment of the sleeve to expand into engagement with the casing wall to block the perforations or cracks. The cylinder includes a sleeve ejecting piston which may be urged to rapidly eject the sleeve from the cylinder by pressure fluid conveyed to the cylinder by coilable tubing or by a gas-generating charge material electrically connected to an E-line which also may be used to deploy the cylinder into its working position in the well.

Apparatus and method for blocking well perforations

Fractures are initiated or extended within an earth formation from a well which includes a tubing string extending to a wellbore space adjacent the fracture zone from a conventional wellhead. Carbon dioxide, nitrogen or a similar highly expansible fluid is pumped into the wellbore space and/or at least a portion of the tubing string at a pressure greater than the fluid critical pressure and greater than the fracture initiation or extension pressure required in the formation zone. A perforating gun is fired or a shear disk is actuated to release the expansible fluid to flow into the formation at an initial velocity and kinetic energy which substantially exceeds that which is obtained with water or similar conventional fracturing fluids so as to initiate or extend hydraulic fractures with a minimum radius of curvature with respect to the wellbore.

High-pressure well fracturing method using expansible fluid

Fluid production or injection wells may be used to transmit or receive seismic signals by lowering a signal transmitting device within a tubing string disposed in the well and exerting a pressure fluid force on a free bottom end of the tubing string to cause the tubing string to helically deflect within the well and engage the wellbore wall firmly over a large portion of the tubing string to enhance the quality and intensity of the signal transmitted between the transmitting device and the earth formation penetrated by the well.

Signal transmission through deflected well tubing

Subterranean mineral seams, such as coal, which have been penetrated by gas production wells are stimulated to produce additional gas by placing a liquid, such as a solvent for coal, in the wellbore and in communication with a tubing extending within the wellbore and having a frangible shear disk assembly disposed therein. Pressure is increased inside the tubing string by pumping gas and/or liquid into the tubing string in sufficient quantity to cause the shear disk to release fluid pressure to act on the fluid in the open hole wellbore portion so that a substantial pressure pulse is exerted on the coal seam to effect rubblization of the coal to form a cavity and release entrapped or adsorbed gas for production up through the well. Imposition of rapid and cyclic pressure pulses on the coal seam at pressures up to 5000 psi above the in situ stress improves production of gas therefrom.

Method of stimulating gas-producing wells

Methods are provided for overpressured perforating and fracturing of a subsurface formation in a substantially deviated well. A perforating gun is run into the well and is pushed through the deviated portion thereof on a coiled tubing string. The coiled tubing string contains an internal supporting pressure which is high enough to prevent collapse of the coiled tubing string prior to perforation of the well and which is low enough to avoid rupturing the coiled tubing string. After the perforations are formed and the fractures are initiated, the supporting gas pressure in the coiled tubing string is bled off to the atmosphere and the coiled tubing string and perforating gun are retrieved.

Overpressured fracturing of deviated wells

Slurries of particulate solids wastes are injected into a disaggregated earth formation through an injection well by predetermining the formation to have a compressive stress in a range of about 300 psi to 2500 psi, a porosity of at least about twenty percent (20%) and disposed between overburden and underburden layers which have a substantially lower permeability than the disposal zone. The disposal zone is disaggregated or 'liquified' by injecting substantially solids-free liquid followed by injection of the solids-laden slurry.

Slurry injection into disaggregated earth formations

Hydraulic fractures are initiated or extended into earth formations from a first well by filling a space within the wellbore and a tubing string extending within the well with a fracturing fluid, placing the first well in fluid flow communication with a tubing string extending within a second well and increasing the pressure of fluid in the respective tubing strings sufficient to initiate or extend the fracture. The second well serves as an accumulator for accumulating a sufficient charge of pressure fluid, such as gas, to drive the fracturing fluid in the first well into the formation to a suitable extent.

Over-pressured well fracturing method

Gas blowouts in wells are controlled by injecting a cohesive aqueous gel composition of hydroxypropyl guar gum, a borate salt cross-linking agent and a weighting agent such as silica flour, barite, hematite or iron oxide. The kill fluid is less susceptible to atomization than weighted drilling fluids, is readily available in most oil and gas field operations and may be rapidly prepared in quantities suitable for injecting into a well to control a gas blowout.

Method for killing a gas blowout of a well

Perforation tunnels and other voids or spaces in earth formations in communication with wells are sealed more effectively by injecting and pre-packing resin-coated particulates (sand) into such tunnels or voids and allowing the sand to consolidate to form a substantially rigid, permeable mass. A lead slurry of relatively fine grained cement is then injected to fill the interstices formed in the permeable material occupying the tunnels or voids. A larger or more coarse grain cement is then injected to form a substantially impermeable, rigid filter cake at the interface of the wellbore and the permeable mass to prevent loss of cement slurry out of the tunnels or voids before the cement is set. Vertical and deviated or generally horizontal wellbores having perforation tunnels or voids which suffer unwanted cement drainage prior to setting of conventional oil well cements are more effectively sealed by the sequential injection of the permeable material followed by injection of settable cement slurries.

Squeeze cementing method for wells

Hydraulic fractures are initiated or extended into fluid-producing earth formations from a cased well by filling a space within the casing adjacent the formation zone of interest with liquid which extends into a tubing string and forming a pressure gas charged portion of the tubing string by introducing pressure gas or liquid into the tubing string to compress a column of gas therein to a pressure which exceeds the formation fracture breakdown pressure. By perforating the casing or, if perforations already exist, releasing a frangible disk type closure interposed in the tubing string, the gas charge in the tubing string forces fluid into the formation at sustained pressure and flow conditions not attainable by surface pumped fracture fluids.

Water injection wells are fractured by a proppant-laden fracturing fluid to create a propped fracture and wherein the proppant-laden fluid is followed by injection of a substantially proppant-free fluid so that the near wellbore portion of the fracture is free of proppant to minimize pressure drop during water injection and to produce higher injection rates for a given injection pressure. The fracture treatment may include the use of viscous fracturing and displacement fluids which are degraded by the injection of acid-bearing fluids at the end of the fracture treatment cycle. Stimulation or displacement liquid (water) injection may commence immediately after the fracture treatment and may be alternated with miscible gas injection.

Injection well fracturing method

A hydraulic fracturing method for earth formations which are penetrated by inclined wellbores wherein the near wellbore region which exhibits the maximum tensile stress in response to hydraulic pressure in the wellbore is determined, and cased wellbores are perforated at the point of maximum tensile stress resulting from fracture initiation. The fracture is subsequently propagated and propped open by proppant-laden fluids having progressively increasing proppant concentrations so that the near wellbore region of the fracture is held propped open to maintain sufficient conductivity between the main fracture body and the wellbore.

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Anchorage, AK, United States of America

Joseph H Schmidt