Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: The present invention provides methods, lightweight well cement compositions and additives for the well cement compositions. The methods of the invention for sealing pipe in a well bore penetrating a zone or formation which readily fractures at low hydrostatic pressure is basically comprised of the steps of providing a lightweight cement composition comprised of a hydraulic cement, water and an additive comprising a suspension of microspheres in water gelled with sodium bentonite, placing the cement composition in the annulus between the pipe and the well bore and allowing the cement composition to set.

Abstract: Methods and compositions for cementing subterranean zones penetrated by well bores are provided. The methods are basically comprised of the steps of providing a cement composition which comprises a hydraulic cement, sufficient water to form a slurry and a dispersing agent comprising a tetrapolymer formed of methacrylic acid, methacrylate, methallyl sulfonic acid and ethoxylated acrylic acid. The cement composition is placed in the subterranean zone to be cemented and allowed to set into an impermeable solid mass therein.

Abstract: Storable water-microsphere suspensions for use in well cements and methods of cementing well bores are provided. The storable water-microsphere suspensions are basically comprised of water, microspheres and an effective amount of a suspending agent selected from the group consisting of microfine or colloidal materials and gel forming polymers.

Abstract: The present invention provides stable well cementing methods and compositions for sealing subterranean zones penetrated by well bores. The improved thermally stable and degradation resistant well cement compositions are basically comprised of a hydraulic cement, sufficient water to form a pumpable slurry, an aqueous hydrogenated styrene-butadiene rubber latex and a latex stabilizer present in an amount sufficient to stabilize the hydrogenated styrene-butadiene latex.

Abstract: The present invention provides methods, lightweight well cement compositions and additives for the well cement compositions. The methods of the invention for sealing pipe in a well bore penetrating a zone or formation which readily fractures at low hydrostatic pressure is basically comprised of the steps of providing a lightweight cement composition comprised of a hydraulic cement, water and an additive comprising an aqueous suspension of microspheres containing a water swellable clay suspending agent, placing the cement composition in the annulus between the pipe and the well bore and allowing the cement composition to set.

Abstract: The present invention provides improved compositions and methods for cementing casing strings in deep water offshore formations penetrated by well bores. The cement composition basically comprises hydraulic cement, water, an environmentally degradable water reducing and dispersing additive, an environmentally degradable set retarding additive and an environmentally degradable compressive strength and set accelerating additive.

Abstract: Environmentally acceptable well cement fluid loss control additives, cement compositions including the additives and methods of using the compositions are provided. The environmentally acceptable fluid loss control additives are comprised of ethoxylated hydroxyethylcellulose having a reduced molecular weight.

Abstract: A method and apparatus for maintaining the fluid column in an annulus are provided. The fluid column support, or fluid column seal is disposed about a second casing being lowered into a well through a first casing already cemented in the well. The fluid column support includes a seal connected to the second casing that engages the first casing as it is lowered therethrough. The seal will allow flow in an upward direction but prevents downward flow. The seal will support, or maintain a fluid column in the annulus between the first and second casing in the event that the fluid level below the seal drops for any reason, such as lost circulation or the failure of a buoyancy chamber in the second casing. The fluid seal, in conjunction with stage tools, provides hydrostatic pressure in the well to maintain proper fluid placement therein.

Abstract: A method and product is disclosed which provides emulsion stability and filtration control to invert emulsion drilling fluids. The product comprises a blend of a carboxylic acid terminated polyamide and a mixture produced by the Diels-Alder reaction of dienophiles, preferably carboxylic acids, polycarboxylic acids, acid anhydrides, or combinations or mixes thereof, with a mixture of fatty acids and resin acids. The product is extremely effective, decreasing by about two-thirds the amount of emulsifier generally required to formulate an effective drilling fluid. The product also greatly reduces and in many cases eliminates the need for conventional fluid loss additives, and additionally provides electrical stability. Moreover, the product has a pour point as low as about 20 degrees Fahrenheit with minimal solvents, thereby eliminating the need to ship large amounts of inert material for use, and may be transported in a highly active state.

Abstract: The current invention provides improved methods and compositions for completing a well bore. In one aspect, the current invention provides a process for preparing a foamed cement composition. The process utilizes air to foam the cement after the air has been treated to lower the oxygen content below that concentration necessary to support combustion. Additionally, the current invention provides a process for completing a well bore using foamed cement wherein the foam is generated with reduced oxygen content air. Finally, the current invention provides a foamed cement composition wherein the gaseous portion of the composition is air having a reduced oxygen content.

Abstract: Methods and compositions for sealing subterranean zones penetrated by well bores are provided. The methods basically comprise the steps of introducing a sealing composition into the subterranean zone comprised of a hydraulic cement, sufficient water to form a slurry and a rapidly acting thixotropy providing gelling agent, and allowing the sealing composition to remain at rest in the zone whereby the sealing composition rapidly gels and then sets into a hard impermeable mass therein.

Abstract: Delayed thixotropic cement compositions and methods of cementing in subterranean zones penetrated by well bores are provided. The novel cement compositions are basically comprised of a hydraulic cement, sufficient water to form a slurry and a water soluble delayed thixotropy imparting additive selected from the group consisting of carbonic acid and alkali metal carbonates.

Abstract: Methods of preparing a particulate flow enhancing additive are provided. The methods are basically comprised of preparing a particulate flow enhancing additive for improving the flow properties of particulate cementitious materials comprising adsorbing a flow inducing chemical on a particulate solid adsorbent material.

Abstract: A real-time method is disclosed for maintaining subterranean formation stability through monitoring the interaction between the formation and fluids introduced into (or produced from ) a wellbore penetrating the formation. The method employs real-time wellbore (in)stability logging methodology. The method is exemplified by a Pore Pressure Transmission (PPT) test. In such test, test fluids are exposed to Pierre II shales (20% w/w NaCl solution and sodium silicate fluid with 20% w/w NaCl, for example) in a PPT apparatus. Membrane efficiency of the two fluids when exposed to the outcrop shale is calculated, and based on the simultaneous acquisition of acoustic data, estimation of a dynamic rock property is made.

Abstract: The present invention provides methods, lightweight well cement compositions and additives for the well cement compositions. The methods of the invention for sealing pipe in a well bore penetrating a zone or formation which readily fractures at low hydrostatic pressure is basically comprised of the steps of providing a lightweight cement composition comprised of a hydraulic cement, water and an additive comprising a suspension of microspheres in water gelled with sodium bentonite, placing the cement composition in the annulus between the pipe and the well bore and allowing the cement composition to set.

Abstract: Methods and compositions for forming permeable cement sand screens in well bores are provided. The compositions are basically comprised of a hydraulic cement, a particulate cross-linked gel containing an internal breaker which after time causes the gel to break into a liquid and water present in an amount sufficient to form a slurry.

Abstract: A method and composition is provided using whey protein as a retarder in a cementing composition for use in cementing operations in a subterranean zone penetrated by a well bore.

Abstract: The present invention provides improved compositions and methods for sealing pipe in a well bore. The compositions which harden into highly resilient solid masses having high strengths are basically comprised of a hydraulic cement, an aqueous rubber latex, an aqueous rubber latex stabilizing surfactant and silica hydrophobicized with silicon oil.

Abstract: Methods and compositions for cementing subterranean zones penetrated by well bores are provided. The methods are basically comprised of the steps of providing a cement composition which comprises a hydraulic cement, sufficient water to form a slurry and a dispersing agent comprising a tetrapolymer formed of methacrylic acid, methacrylate, methallyl sulfonic acid and ethoxylated acrylic acid. The cement composition is placed in the subterranean zone to be cemented and allowed to set into an impermeable solid mass therein.