Abstract: A method is disclosed for controlling pressure in a wellbore during drilling. The method includes operating a drilling system to have a first fluid pressure gradient inside a drillstring extending from the earth's surface to a drill bit at the bottom of the wellbore. The drilling system has a second fluid pressure gradient lower than the first fluid pressure gradient in an annular space between the drillstring and the wellbore from a selected depth in the wellbore to the earth's surface. Introduction of drilling fluid to the inside of the drillstring is stopped, and fluid flow in the annular space from a point below the selected depth to a point above the selected depth is selectively controlled to cause a substantially constant fluid pressure at a predetermined depth in the wellbore.

Abstract: A process is disclosed for stimulating the activity of microbial consortia in a subterranean formation to convert hydrocarbons to methane, which can be produced. Fluid and rock of the formation are analyzed. The presence of microbial consortia is determined and a characterization made (preferably genetic) of at least one microorganism of the consortia, at least one being a methanogenic microorganism. The characterization is compared with at least one known characterization derived from a known microorganism having one or more known physiological and ecological characteristics. This information, together with the information obtained from the analysis of the fluid and rock, is used to determine an ecological environment that promotes in situ microbial degradation of formation hydrocarbons and promotes microbial generation of methane by at least one methanogenic microorganism of the consortia. This information is then used as the basis for modifying the formation environment to produce methane.

Abstract: The invention relates to a process of manufacturing a pressurized multi-component liquid from a pressurized, multi-component stream, such as natural gas, which contains C5+ components and at least one component of C1, C2, C3, or C4. The process selectively removes from the multi-component stream one or more of the C5+ components that would be expected to crystallize at the selected temperature and pressure of the pressurized multi-component liquid product and leaves in the multi-component stream at least one C5+ component. The multi-component stream is then liquefied to produce a pressurized liquid substantially free of crystallized C5+ components. The removal of the C5+ components can be by selective fractionation or crystallization.

Abstract: A process for removing hydrocarbons less volatile than methane from a pressurized liquid natural gas (PLNG). PLNG is heated in a heat exchanger, thereby vaporizing at least a portion of the PLNG. The partially vaporized PLNG is passed to a fractionation column. A liquid stream enriched with hydrocarbons (C2+ or C3+) less volatile than methane is withdrawn from a lower portion of the fractionation column and a vapor stream lean in the hydrocarbons less volatile than methane is withdrawn from an upper portion of the fractionation column. The withdrawn vapor stream is passed to the heat exchanger to condense the vapor to produce PLNG lean in hydrocarbons less volatile than methane.

Abstract: A thermodynamic cycle is disclosed that uses compression and expansion to generate refrigeration or power in which at least some of the compression is effected by hydrostatic head of the heat-exchange medium used in the cycle. In a refrigeration cycle, the head of a heat-exchange medium in the refrigeration cycle is used to compress the heat-exchange medium. A vaporous heat-exchange medium is introduced into the upper end of a down riser that extends downwardly through a heat sink. The vaporous heat-exchange medium descends through the down riser and the head of the heat-exchange medium compresses the heat-exchange medium. The heat generated by the compression is transferred to the heat sink. The heat-exchange medium is then pumped up through a return riser and passed through a pressure expansion means and evaporator. From the evaporator the heat-exchange medium is returned to the upper end of the down riser for recycling.

Abstract: A method is disclosed of estimating a property of a hydrocarbon-bearing formation penetrated by at least one injection well through which fluid is injected into the formation and penetrated by at least one production well through which fluid is produced from the formation. The injection rates of fluid through the injection wells are periodically varied and measured at substantially regular time intervals and measurements are also made of the production rate of fluid produced through the production well. A series of production well response delays, &tgr;, are selected. A set of correlation coefficients between the injection rate for each injection well and the production rate as a function of &tgr; are determined. From each set of correlation coefficients, a time lag, &tgr;max, corresponding to the maximum correlation coefficient is determined. The &tgr;max is then used to characterize a formation property, such as channel volume, permeability, or transmissibility.

Abstract: This invention relates to process for liquefying a pressurized gas stream rich in methane. In a first step of the process, a first fraction of a pressurized feed stream, preferably at a pressure above 11,000 kPa, is withdrawn and entropically expanded to a lower pressure to cool and at least partially liquefy the withdrawn first fraction. A second fraction of the feed stream is cooled by indirect heat exchange with the expanded first fraction. The second fraction is subsequently expanded to a lower pressure, thereby at least partially liquefying the second fraction of the pressurized gas stream. The liquefied second fraction is withdrawn from the process as a pressurized product stream having a temperature above −112° C. and a pressure at or above its bubble point pressure.

Abstract: A method for recovering oil in a reservoir by generating chemical microexplosions in the reservoir. The invention treats the hydrocarbon-bearing reservoir by decomposing in situ at least one imidazolidone derivative, thereby generating heat, shock, and CO2. A preferred method comprises the steps of depositing an imidazolidone derivative into the formation and depositing an acid into the formation to cause the imidazolidone derivative to decompose and generate heat and gas.

Abstract: A thermodynamic cycle is disclosed that uses compression and expansion to generate refrigeration or power in which at least some of the compression is effected by hydrostatic head of the heat-exchange medium used in the cycle. In a refrigeration cycle, the head of a heat-exchange medium in the refrigeration cycle is used to compress the heat-exchange medium. A vaporous heat-exchange medium is introduced into the upper end of a down riser that extends downwardly through a heat sink. The vaporous heat-exchange medium descends through the down riser and the head of the heat-exchange medium compresses the heat-exchange medium. The heat generated by the compression is transferred to the heat sink. The heat-exchange medium is then pumped up through a return riser and passed through a pressure expansion means and evaporator. From the evaporator the heat-exchange medium is returned to the upper end of the down riser for recycling.

Abstract: A process is disclosed for producing from a pressurized methane-rich gas stream a pressurized methane-rich liquid stream having a temperature above −112° C. (−170° F.) and having a pressure sufficient for the liquid to be at or below its bubble point. In this process, a methane-rich liquid stream having a temperature below about −155° C. (−247° F.) is supplied and its pressure is increased. A pressurized methane-rich gas to be liquefied is supplied and introduced to the pressurized methane-rich liquid stream at a rate that produces a methane-rich liquid stream having a temperature above −112° C. (−170° F.) and a pressure sufficient for the liquid to be at or below its bubble point.

Abstract: A method is disclosed for loading pressurized liquefied natural gas (PLNG) into a plurality of containers containing pressurized vapor, wherein the containers are loaded in succession. The containers may be onshore or onboard a ship or other ocean transporting vessel. As a first step, the liquefied gas is introduced into the containers, thereby discharging the vapor therefrom. Vapor discharged from the containers is passed to auxiliary storage tanks comprising a first tank and a second tank. Vapor from at least one of the tanks is withdrawn and passed to a vapor utilization means such as a liquefaction plant for liquefaction of the vapor or to an engine or turbine for use of the vapor as fuel. Fluid flow to and from the first and second tanks is regulated to assure that the total flow rate of vapor to the vapor utilization means remains at a relatively constant flow rate.

Abstract: A process is disclosed to remove at least one high volatility component, such as nitrogen, from a pressurized natural gas to produce pressurized liquefied natural gas that is lean in nitrogen and has a temperature above about −112° C. (−170° F.). A pressurized feed natural gas containing nitrogen is expanded and passed to a fractionation column. The fractionation column produces a first vapor stream that has enhanced nitrogen content and a first liquid stream. The vapor stream is cooled to produce a vapor phase and a liquid phase. The vapor and liquid phases are then phase separated to produce a second vapor stream and a second liquid stream. The second liquid stream is returned to the fractionation column as reflux. The second vapor stream is preferably used to cool the incoming feed stream. The first liquid stream is removed from the fractionation system as a product stream lean in nitrogen.

Abstract: A process is disclosed for conveying gas stream rich in methane, such as natural gas. In the first step of the process, gas is supplied to a pipeline at an entry pressure that is substantially higher than the output pressure of the pipeline. The drop in pressure in the pipeline causes a lowering of the gas temperature, preferably to a temperature below about −29° C. (−20° F.). The entry pressure of the gas to the pipeline is controlled to achieve a predetermined output pressure of the gas from the pipeline. Output gas from the pipeline is then liquefied to produce liquefied gas having a temperature above about −112° C. (−170° F.) and a pressure sufficient for the liquid to be at or below its bubble point temperature. The pressurized liquefied gas is then further transported in a suitable container.

Abstract: A method is disclosed for unloading a plurality of containers containing pressurized liquefied gas in which the liquefied gas has a temperature above −112° C. A pressurized displacement liquid is fed to a first of the plurality of containers to discharge the pressurized liquefied gas therefrom. The displacement liquid is then pumped from the first container to a second container of the plurality of containers to discharge liquefied gas therefrom. As the displacement liquid is removed from the first container, the space caused by the removal of the displacement liquid is filled with a vapor at a lower pressure than the pressure of displacement liquid. Fluid communication between the first second containers is then severed and the above steps are repeated for all containers in succession, except that for the last container in the series the displacement liquid is pumped therefrom to an auxiliary container for storage rather than to another container.

Abstract: A process is disclosed to remove a high-volatility component, such as nitrogen, from a feed stream rich in methane to produce a product substantially free of the high-volatility component. The feed stream is expanded and fed to a phase separator which produces a vapor stream and a liquid stream. The vapor stream is enriched in the volatile component. The liquid stream, which is lean in the volatile component and rich in methane, is pumped to a higher pressure and heated to produce a pressurized liquefied product stream having a pressure sufficient for the product stream to be at or below its bubble point and having a temperature above about −112° C. (−170° F.).

Abstract: A process is disclosed for reliquefying boil-off gas produced by pressurized liquid natural gas. In this process, refrigeration duty is provided to a heat exchanger by means of a refrigeration cycle. Pressurized natural gas is cooled by the heat exchanger and then expanded to a lower pressure to produce a liquid stream that is passed to a first phase separator. A boil-off vapor is passed through the heat exchanger and it is then compressed and cooled before being recycled back through the heat exchanger. The compressed, cooled boil-off gas is then expanded and passed to a second phase separator. A vapor stream produced by the second separator is removed from the process. A liquid stream produced by the second phase separator is passed to the first phase separator to produce a pressurized liquid having a temperature above about −112° C. and a pressure sufficient for the liquid to be at or below its bubble point.

Abstract: A process is disclosed for converting liquefied natural gas (LNG), at a temperature of about -162.degree. C. (-260.degree. F.) and a pressure near atmospheric pressure, to a pressurized liquefied natural gas (PLNG) having a temperature above -112.degree. C. (-170.degree. F.) and a pressure sufficient for the liquid to be at or near its bubble point and at the same time producing energy derived from the cold of the LNG. The LNG is pumped to a pressure above 1,380 kPa (200 psia) and passed through a heat exchanger. A refrigerant as a working fluid in a closed circuit is passed through the heat exchanger to condense the refrigerant and to provide heat for warming the pressurized LNG. The refrigerant is then pressurized, vaporized by an external heat source, and then passed through a work-producing device to generate energy.

Abstract: A process is disclosed for unloading a plurality of containers having pressurized liquefied gas contained therein. A pressurized displacement gas is fed to a first container or group of containers to discharge the liquefied gas therefrom. The displacement gas is then withdrawn from the first container or group and it is separated into a first vapor stream and a second vapor stream. The first vapor stream is heated and passed to the first container or group. The second vapor stream is fed to a second container or group to discharge liquefied gas therefrom. Communication between the first container or group and the second container or group is severed and the foregoing steps are repeated for all of the containers in succession, with only the last container or group emptied of liquid remaining at the pressure of the displacement gas, and all of the containers at the end of the process except the last container or group being filled with a lower pressure vapor.

Abstract: Disclosed is a method for estimating properties of a multi-component fluid using pseudocomponents. The fluid is characterized using a set of base components and a set of fluid compositions is defined that corresponds to fluid compositions expected to occur in computations of interest. Pseudocomponents are defined to represent the multi-component fluid by (i) defining an ordered set of vectors corresponding to a characteristic of the base components, each vector containing one entry for each base component, the first vector being most representative of the set of compositions according to a predetermined criterion and each vector thereafter in the set being less representative of the set of compositions than the vector before it, and (ii) selecting a subset of the ordered set that comprises the first vector and a predetermined number of vectors immediately thereafter, the subset of vectors corresponding to a pseudocomponent characterization of the multi-component fluid.

Abstract: A process for using the cold of pressurized liquefied natural gas (PLNG) to compress boil-off vapors produced by handling of liquefied natural gas to produce a higher pressure gas product and at the same time produce power that preferably provides at least part of the power for the process. The PLNG is pressurized, passed to a first heat exchanger for vaporization, and the vaporous material is passed to a second heat exchanger for further heating to produce a first gas product. A refrigerant is circulated in a closed cycle through the first heat exchanger to heat the PLNG, through a pump to pressurize the refrigerant, through a second heat exchanger to vaporize the refrigerant, and through a work-producing device to generate energy. Boil-off gas is compressed and passed through the first heat exchanger, further compressed, and then passed through the second heat exchanger to produce a second gas product.