Abstract: Predicting sand production in a wellbore. A first set of characteristics is determined for a formation in the wellbore, wherein determining uses a plastic model of the formation, and wherein the first set of characteristics comprises a yield surface, a failure surface, a stress total strain, an elastic strain, and a plastic-strain relationship. A relationship among a second set of characteristics of the wellbore is determined using an effective stress model, wherein the second set comprises a drawdown pressure, a production rate, pore pressure, a temperature and a viscosity of a fluid in the wellbore, a fluid flow pressure in the wellbore, a drag force of fluid flow in the wellbore, and a type of fluid flow in the wellbore. A critical total strain is determined for the formation using the first set of characteristics and the relationship. The critical total strain is calibrated using a thick wall test.

Abstract: In general, in one aspect, the invention relates to a method for determining properties of a subterranean formation.

Abstract: The invention relates to a method for determining maximum horizontal stress in an earth formation. The method includes obtaining fast shear wave velocities (Vs1) and slow shear wave velocities (Vs2) for various depths in the earth formation, calculating shear wave anisotropy (Adata) using Vs1 and Vs2, obtaining vertical stress (Sv) and minimum horizontal stress (Sh) for the formation, representing maximum horizontal stress (SH) using a parameterized function having at least one parameter and using Sh and Sv as input, determining a value of the at least one parameter by minimizing a cost function that represents a measure of difference between Adata and Apred for the various depths and Apred is predicted shear wave anisotropy determined using Sv, Sh, and SH, calculating SH using the parameterized function and the value of the at least one parameter, and storing SH in relation to the earth formation.

Abstract: The invention is a silicon substituted oxyapatite compound (Si—OAp) for use as a synthetic bone biomaterial either used alone or in biomaterial compositions. The silicon substituted oxyapatite compound has the formula Ca5(PO4)3-x(SiO4)xO(1-x)/2, where 0<x<1.0.

Abstract: Predicting sand production in a wellbore. A first set of characteristics is determined for a formation in the wellbore, wherein determining uses a plastic model of the formation, and wherein the first set of characteristics comprises a yield surface, a failure surface, a stress total strain, an elastic strain, and a plastic-strain relationship. A relationship among a second set of characteristics of the wellbore is determined using an effective stress model, wherein the second set comprises a drawdown pressure, a production rate, pore pressure, a temperature and a viscosity of a fluid in the wellbore, a fluid flow pressure in the wellbore, a drag force of fluid flow in the wellbore, and a type of fluid flow in the wellbore. A critical total strain is determined for the formation using the first set of characteristics and the relationship. The critical total strain is calibrated using a thick wall test.

Abstract: The invention is a silicon substituted oxyapatite compound (Si—OAp) for use as a synthetic bone biomaterial either used alone or in biomaterial compositions. The silicon substituted oxyapatite compound has the formula Ca5(PO4)3-x(SiO4)xO(1-x)/2, where 0<x<1.0.

Abstract: A method for performing an oilfield operation at a wellsite having a drilling rig configured to advance a drilling tool into a subsurface formation. The method includes generating a borehole temperature model for an area of interest using water depth information and a vertical stress model, generating a formation temperature model using the borehole temperature model, generating a mud-weight pressure model using the formation temperature model and pressure coefficients, generating a formation pore pressure model using the mud-weight pressure model, and adjusting the oilfield operation based on the formation pore pressure model.

Abstract: This invention relates to a bioactive artificial sintered composition for providing a morphology capable of consistently supporting bone cell activity thereon. The composition comprises stabilized calcium phosphate phases developed by the conversion of a hydroxyapatite substance in the presence of stabilizing entities at sintering temperatures into insolubilized and stabilized tricalcium phosphate. The present invention has numerous applications in medical diagnostics for the assessment of abnormal bone cell activity as well as for medical therapeutics, including bone and dental tissue replacement and repair as well as for ex vivo bone graft tissue engineering.

Abstract: The invention is a silicon substituted oxyapatite compound (Si—OAp) for use as a synthetic bone biomaterial either used alone or in biomaterial compositions. The silicon substituted oxyapatite compound has the formula Ca5(PO4)3-x(SiO4)xO(1-x)/2, where 0<x<1.0.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 ?. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, including measuring sonic velocity properties in formations surrounding the substantially vertical section of the wellbore; measuring sonic velocity properties in formations surrounding the deviated section of the wellbore; and determining, from the measured velocities, all of the transverse isotropic elastic constants of the region.

Abstract: A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, including measuring sonic velocity properties in formations surrounding the substantially vertical section of the wellbore; measuring sonic velocity properties in formations surrounding the deviated section of the wellbore; and determining, from the measured velocities, all of the transverse isotropic elastic constants of the region.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 Å. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 Å. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 Å. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 Å. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.

Abstract: The present invention is directed to a synthetic biomaterial compound based on stabilized calcium phosphates and more particularly to the molecular, structural and physical characterization of this compound. The compound comprises calcium, oxygen and phosphorous, wherein at least one of the elements is substituted with an element having an ionic radius of approximately 0.1 to 1.1 ?. The knowledge of the specific molecular and chemical properties of the compound allows for the development of several uses of the compound in various bone-related clinical conditions.

Abstract: A method for producing thick ceramic films of greater than 10 .mu.m on selected substrates is described. Conventional sol gel solutions are loaded with up to about 90% by weight of finely divided ceramic particles and mixed. The resulting slurry or paint can be either spun or dip coated or sprayed or painted onto a planar or other substrate, fired to remove the organic materials and to develop a microcrystalline structure. The fired film may then be heated. Composite films are also contemplated.