Abstract: The invention is related to a method to clean a matrix-fracture interface of fractured tight sandstone, tight carbonate, and tight shale reservoirs. The method involves the injection of at least one fluid into a reservoir, wherein the fluid is gas, a surfactant, a surfactant solution, or combinations thereof. In some embodiments, the reservoir has previously been stimulated mechanically by hydraulic fracturing.

Abstract: The present invention relates to a method to enhance oil recovery from a hydrocarbon reservoir. One aspect of the invention includes injecting low-salinity water into the reservoir followed by the injection of a surfactant diluted in low-salinity water, and alternating the injections of the low-salinity water and the surfactant diluted in the low-salinity water. A gas is then injected into the reservoir. The invention improves the effectiveness of the surfactant and the gas by reducing the salinity of the reservoir by injecting low-salinity water into the reservoir.

Abstract: The present invention relates to a method to enhance oil recovery from a hydrocarbon reservoir. One aspect of the invention includes injecting high salinity water into the reservoir followed by alternating the injection of low salinity water and gas.

Abstract: The present invention relates to a method to enhance oil recovery from a hydrocarbon reservoir. One aspect of the invention includes injecting low salinity water into the reservoir followed by the injection of a surfactant diluted in low salinity water, and alternating the injections of the low salinity water and the surfactant diluted in the low salinity water. The invention improves the effectiveness of the surfactant by reducing the salinity of the reservoir by injecting low-salinity water into the reservoir.

Abstract: An integrated electronics housing contains both system electronics and power generation circuits for a two-axis tracker assembly having a CPV solar array. The housing contains at least a communication bus, motion control circuits, and inverter circuits, and acts as the local system control point for that tracker mechanism. The inverter circuits generate three-phase AC voltage that is supplied to a grid interface transformer. Each inverter receives a bipolar DC voltage supplied from its own set of CPV cells. The motion control circuits move the CPV cells of the tracker mechanism to angular coordinates resulting from a solar tracking algorithm. The communication bus connects to the motion control circuits and the inverter circuits to facilitate communications of information, including parameters of power being generated by the inverter circuits, between the motion control circuits and the AC inverter circuits to fine tune the AC power generated out of the tracker mechanism.

Abstract: Various methods and apparatus are described for a photovoltaic system. In an embodiment, pluralities of three-phase Alternating Current (AC) inverter circuits electrically connect into a common three phase AC output. Each of those inverters receives a bipolar DC voltage supplied from its own set of Concentrated PhotoVoltaic (CPV) modules.

Abstract: Various methods and apparatus are described for a photovoltaic system. In an embodiment, a hybrid grounding circuit as well as a ground fault monitoring circuit are in the inverter circuitry with its switching devices that generate three-phase Alternating Current (AC) voltage. The three-phase AC voltage is supplied to a utility power grid interface transformer, where a primary-side common node of the Utility Power grid interface transformer is connected to Earth ground. Each inverter has 1) its own set of isolation contacts to connect as well as isolate this particular inverter from the utility grid interface transformer, and 2) control components in the ground fault monitoring circuit for controlling operation of the isolation contacts based off a presence of the ground fault detected by the ground fault monitor circuit for that inverter. The inverter circuit receives a DC voltage supplied from its own set of ungrounded Concentrated PhotoVoltaic modules.

Abstract: Various methods and apparatus are described for an integrated remotely controlled photovoltaic system having a number of components. A central backend server management system is configured to facilitate management of two or more solar arrays at a remote site from a client device connected over a public wide area network (WAN). An integrated electronics housing contains multiple circuits, including power generation inverter circuits and solar array motion control circuits for one or more PhotoVoltaic (PV) solar arrays at the remote site. The multiple circuits cohesively exist in the integrated electronics housing and actually perform better because of the interconnectivity. The communication circuitry within the integrated electronics housing is configured to establish secure communications over the WAN with the central backend server management system. The integrated electronics housing acts as the local system control point for the first solar array.

Abstract: A plurality of concentrated photovoltaic (CPV) arrays located at a solar site may be operated and communicate with a central backend management system over a public wide area network. Each of the CPV arrays is associated with a different system control point (SCP). Each SCP includes circuitry with test points for performance monitoring of at least 1) an electrical power generating circuitry that generates alternating current (AC) voltage output and 2) a tracker motion control circuit to control a position of the CPV array for that SCP, and 1) configured logic, 2) resident software applications, or 3) any combination of both in the SCP is configured to collect the performance monitoring information and store in a memory of the SCP. The information from the circuitry with test points for performance monitoring is communicated to the central backend management system over the public wide area network.

Abstract: An integrated electronics housing contains both system electronics and power generation circuits for a two-axis tracker assembly having a CPV solar array. The housing contains at least a communication bus, motion control circuits, and inverter circuits, and acts as the local system control point for that tracker mechanism. The inverter circuits generate three-phase AC voltage that is supplied to a grid interface transformer. Each inverter receives a bipolar DC voltage supplied from its own set of CPV cells. The motion control circuits move the CPV cells of the tracker mechanism to angular coordinates resulting from a solar tracking algorithm. The communication bus connects to the motion control circuits and the inverter circuits to facilitate communications of information, including parameters of power being generated by the inverter circuits, between the motion control circuits and the AC inverter circuits to fine tune the AC power generated out of the tracker mechanism.

Abstract: In an embodiment, inverter circuitry has switching devices that generate three-phase AC voltage that is supplied to a utility power grid interface transformer. A high impedance circuit as well as a ground fault monitoring circuit couple to the inverter circuit. The high impedance circuit is configured to periodically create a path to Earth ground, and thus, completes the Earth ground electrical path back to the ground fault detection circuit. A set of isolation contacts at the AC 3-phase power output connect as well as isolate this particular inverter from the utility grid interface transformer. Control components in the ground fault monitoring circuit control the operation of the isolation contacts based off a presence of a ground fault in ungrounded solar arrays that supply DC power to this ungrounded inverter circuitry when the ground fault is detected by the ground fault monitor circuit for that ungrounded inverter.

Abstract: Various methods and apparatus are described for an integrated remotely controlled photovoltaic system having a number of components. A central backend server management system is configured to facilitate management of two or more solar arrays at a remote site from a client device connected over a public wide area network (WAN). An integrated electronics housing contains multiple circuits, including power generation inverter circuits and solar array motion control circuits for one or more PhotoVoltaic (PV) solar arrays at the remote site. The multiple circuits cohesively exist in the integrated electronics housing and actually perform better because of the interconnectivity. The communication circuitry within the integrated electronics housing is configured to establish secure communications over the WAN with the central backend server management system. The integrated electronics housing acts as the local system control point for the first solar array.

Abstract: Various methods and apparatus are described for a photovoltaic system. In an embodiment, pluralities of three-phase Alternating Current (AC) inverter circuits electrically connect into a common three phase AC output. Each of those inverters receives a bipolar DC voltage supplied from its own set of Concentrated PhotoVoltaic (CPV) modules.

Abstract: Various methods and apparatus are described for a photovoltaic system. In an embodiment, a hybrid grounding circuit as well as a ground fault monitoring circuit are in the inverter circuitry with its switching devices that generate three-phase Alternating Current (AC) voltage. The three-phase AC voltage is supplied to a utility power grid interface transformer, where a primary-side common node of the Utility Power grid interface transformer is connected to Earth ground. Each inverter has 1) its own set of isolation contacts to connect as well as isolate this particular inverter from the utility grid interface transformer, and 2) control components in the ground fault monitoring circuit for controlling operation of the isolation contacts based off a presence of the ground fault detected by the ground fault monitor circuit for that inverter. The inverter circuit receives a DC voltage supplied from its own set of ungrounded Concentrated PhotoVoltaic modules.

Abstract: A ground fault detector interrupter (GFDI) is described. The GFDI configured for use with a DC power supply and comprises the following elements. A ground current path is provided for coupling a ground terminal of the DC power supply and a system ground. A grounding switch is placed in the ground current path. A current detector is configured to detect a ground current in the ground current path. A controller is configured to compare the ground current with a predefined current set point and output a fault indication signal if the ground current exceeds the predefined current set point. The fault indication signal results in the grounding switch being open.

Abstract: This invention relates to methods and systems for reducing transaction costs and minimizes turnover in the trading of futures contracts. The invention further describes an algorithm whose output is a unique method of investing in futures contracts that reduces the rate of turnover, and thus the cost of trading, of certain common trading strategies. The primary application of this method is to a class of strategies referred to as indexing strategies that incorporate a dynamic asset allocation approach using futures contracts.