Abstract: The present invention provides a method and system in which signals from the surface are sent by changing flow rate of the drilling fluid supplied to the drill string during drilling of a wellbore. The signals are sent based on a fixed or dynamic time period schemes so that the sent signals cross a dynamic threshold value in a known manner. A controller downhole sets the dynamic threshold and determines the number of times a parameter, such as voltage, relating to the changes in the flow rate crosses the set dynamic threshold. Based on the number of the number of crossings and/or the number of crossings and the timing of such crossings, the controller ascertains the signal sent from the surface for use downhole.

Abstract: A system for reverse circulation in a wellbore include equipment for supplying drilling fluid into the wellbore bit via at least an annulus of the wellbore and returning the drilling fluid to a surface location via at least a bore of a wellbore tubular. The system also includes devices for controlling the annulus pressure associated with this reverse circulation. In one embodiment, an active pressure differential device increases the pressure wellbore annulus to at least partially offset a circulating pressure loss. In other embodiments, the system includes devices for decreasing the pressure in the annulus of the wellbore. For offshore application, annulus pressure is decreased to accommodate the pore and fracture pressures of a subsea formation. In still other embodiments, annulus pressure is decreased to cause an underbalanced condition in the well.

Abstract: A method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using a higher-order pressure derivative with respect to time technique to determine the formation pressure during the drawdown. Another method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using at least two analysis techniques to each determine an estimate of the formation pressure during the drawdown.

Abstract: An apparatus and method for isolating a downhole tool section from hydraulic and mechanical noise. Anchoring grippers are used in conjunction with a fluid diverter valve to anchor the tool section to a borehole wall and divert fluid flowing in the drill string away from sensitive test equipment during formation testing.

Abstract: One exemplary APD Device is used with a liner drilling assembly to control wellbore pressure. The APD Device reduces a dynamic pressure loss associated with the drilling fluid returning via a wellbore annulus. Another exemplary APD Device is used to control pressure in a wellbore when deploying wellbore equipment, including running, installing and/or operating wellbore tools. The APD Device is set to reduce a dynamic pressure loss associated with a circulating fluid. The APD Device can also be configured to reduce a surge effect associated with the running of the wellbore equipment. Still another APD Device is used to control pressure in a wellbore when completing or working over a well. Exemplary completion activity can include circulating fluid other than a drilling fluid, such as a gravel slurry. The APD Device can reduce the dynamic pressure loss associated with circulation of both drilling fluid and non-drilling fluid.

Abstract: Methods and control systems are provided for a wellbore drilling system having an active differential pressure device (APD device) in fluid communication with a returning fluid. The APD Device creates a differential pressure across the device, which reduces the pressure below or downhole of the device. In embodiments, a control unit controls the APD Device in real time via a data transmission system. In one arrangement, the data transmission system includes data links formed by conductors associated with the drill string. The conductors, which may include electrical wires and/or fiber optic bundles, couple the control unit to the APD Device and other downhole tools such as sensors. In other arrangements, the data link can include data transmission stations that use acoustic, EM, and/or RF signals to transfer data. In still other embodiments, a mud pulse telemetry system can be used in transfer data and command signals.

Abstract: Methods and control systems are provided for a wellbore drilling system having an active differential pressure device (APD device) in fluid communication with a returning fluid. The APD Device creates a differential pressure across the device, which reduces the pressure below or downhole of the device. In embodiments, a control unit controls the APD Device to provide a selected pressure differential at a wellbore bottom, adjacent a casing shoe, in an intermediate wellbore location, or in a casing. In one arrangement, the control system is pre-set at the surface such that the APD Device provides a substantially constant pressure differential. In other arrangements, the control system measures one or more parameters (e.g., wellbore pressure, formation parameters, BHA parameters, etc.) and adjusts an operating parameter of the APD Device to provide a desired pressure differential. Devices such as an adjustable bypass can be used to control the APD Device.

Abstract: An APD Device provides a pressure differential in a wellbore to control dynamic pressure loss while drilling fluid is continuously circulated in the wellbore. A continuous circulation system circulates fluid both during drilling of the wellbore and when the drilling is stopped. Operating the APD Device allows wellbore pressure control during continuous circulation without substantially changing density of the fluid. The APD Device can maintain wellbore pressure below the combined pressure caused by weight of the fluid and pressure losses created due to circulation of the fluid in the wellbore, maintain the wellbore at or near a balanced pressure condition, maintain the wellbore at an underbalanced condition, reduce the swab effect in the wellbore, and/or reduce the surge effect in the wellbore. A flow restriction device that creates a backpressure in the wellbore annulus provides surface control of wellbore pressure.

Abstract: A wellbore drilling system has an umbilical that carries a drill bit in a wellbore. Drilling fluid pumped into the umbilical discharges at the drill bit bottom and returns through an annulus between the umbilical and the wellbore carrying entrained drill cuttings. An active differential pressure device (APD device), such as a jet pump, turbine or centrifugal pump, in fluid communication with the returning fluid creates a differential pressure across the device, which alters the pressure below or downhole of the device. The APD device can be driven by a positive displacement motor, a turbine, an electric motor, or a hydraulic motor. A controller controls the operation of the APD device in response to programmed instructions and/or one or more parameters of interest detected by one or more sensors. A preferred system is a closed loop system that maintains the wellbore at under-balance condition, at-balance condition or over-balance condition.

Abstract: One or more components of a wellbore drilling assembly utilize a modular construction to facilitate assembly, disassembly, repair and/or maintenance of a wellbore drilling assembly and/or to extend the overall operating capabilities of the drilling assembly. In one embodiment, a modular construction is used for an APD Device, a motor driving the modular APD Device, a comminution device, and an annular seal. Individual modules can be configure have different operating set points, operating parameters and characteristics (e.g., rotational speeds, flow rates, pressure differentials, etc.) and/or different responses to given environmental factors or conditions (e.g., pressure, temperature, wellbore fluid chemistry, etc.). In one embodiment, the high-pressure seals used in conjunction with the APD Device and/or motor is a hydrodynamic seal that provides a selected leak or flow rates. Optionally, the seal is modular to provide different degrees of leak rates and/or different functional characteristics.

Abstract: An active differential pressure device (APD device) in fluid communication with a returning fluid creates a differential pressure across the device, which controls pressure below the APD Device. In embodiments, a control unit controls the APD Device to provide a selected pressure differential at a wellbore bottom, adjacent a casing shoe, in an intermediate wellbore location, or in a casing. In one arrangement, the control system is pre-set at the surface such that the APD Device provides a substantially constant pressure differential. In other arrangements, the control system adjusts an operating parameter of the APD Device to provide a desired pressure differential in response to one or more measured parameters. Devices such as an adjustable bypass can be used to control the APD Device. In other embodiments, one or more flow control devices coupled to the return fluid reduce the effective pressure differential provided by the APD Device.

Abstract: A method and apparatus for of determining a formation parameter of interest. The method includes placing a tool into communication with the formation to test the formation, determining a first formation characteristic during a first test portion, initiating a second test portion, the second test portion having test parameters determined at least in part by the determinations made during the first test portion, determining a second formation characteristic during the second test portion, and determining the formation parameter from one of the first formation characteristic and the second formation characteristic. The apparatus includes a draw down unit and a control system for closed loop control of the draw down unit. A microprocessor in the control system processes signals from a sensor in the draw down unit to determine formation characteristics and to determine test parameters for subsequent test portions.

Abstract: A method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using a higher-order pressure derivative with respect to time technique to determine the formation pressure during the drawdown. Another method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using at least two analysis techniques to each determine an estimate of the formation pressure during the drawdown.

Abstract: A downhole device processes particles entrained in a drilling fluid returning up a wellbore. In one embodiment, the device includes a housing having at least one cutting surface formed in a chamber of a housing. A cutting head disposed in the chamber crushes or comminutes the particles entrained in the drilling fluid to a predetermined size. The device is disposed in the wellbore and processes the entrained particles before they enter a selected wellbore device such as a pump. In certain embodiments, the housing has at least two chambers, wherein the entrained particles are reduced to a first predetermined size in the first chamber, a second predetermined size in the second chamber, etc. Also, the housing can include an operator that generates an energy field that reduces the size of the particles entrained in the drilling fluid to a first predetermined size when the particles flow through the energy field.

Abstract: A borehole wall cleaning apparatus and method for obtaining an improved seal between a fluid sampling device and a portion of the borehole wall. Clean drilling fluid is pumped into a drilling tool using a mud pump. A fluid diverter in the tool diverts all or part of the clean drilling fluid through a port to clear a portion of a borehole wall. A sealing pad is moved against the clean portion. A sampling port is exposed to the sealed portion for sampling and/or testing fluid from the formation.

Abstract: Devices and methods are described for establishing an effective annular seal about between an active pressure differential device and a surrounding wellbore sidewall. In other aspects, the invention provides a means of selectively activating such a seal during drilling operations or other operations wherein drilling mud is flowed through the drill string and returns through the annulus. The annular seal assembly may include an inflatable packer element and a hydraulic inflation system. The hydraulic inflation system uses the fluid pressure provided by drilling mud that is returning to the surface via the annulus to inflate the packer element and set the seal. The hydraulic inflation system also buffers and regulates the fluid pressure setting the packer element to avoid overinflation of the element. In other aspects, the seal assembly may comprise a set of mud cups that are set against the borehole sidewall using a pressure differential across the seal assembly or a spring-biased seal element.

Abstract: An apparatus and method for isolating a downhole tool section from hydraulic and mechanical noise. Anchoring grippers are used in conjunction with a fluid diverter valve to anchor the tool section to a borehole wall and divert fluid flowing in the drill string away from sensitive test equipment during formation testing.

Abstract: Methods for estimating formation pressure from data taken during the drawdown cycle are presented. In one aspect, a method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool having a sample volume and a fluid sampling device. At least one time dependent parameter of interest related to the fluid is determined during the drawdown. The at least one time dependent parameter is analyzed using a plurality of calculation techniques to determine the formation pressure. The techniques include (i) a first pressure derivative technique; (ii) a second pressure derivative technique; (iii) a formation rate analysis technique; (iv) a dp/dt-ratio technique; and (v) a stepwise drawdown technique.

Abstract: Methods and control systems are provided for a wellbore drilling system having an active differential pressure device (APD device) in fluid communication with a returning fluid. The APD Device creates a differential pressure across the device, which reduces the pressure below or downhole of the device. In embodiments, a control unit controls the APD Device to provide a selected pressure differential at a wellbore bottom, adjacent a casing shoe, in an intermediate wellbore location, or in a casing. In one arrangement, the control system is pre-set at the surface such that the APD Device provides a substantially constant pressure differential. In other arrangements, the control system measures one or more parameters (e.g., wellbore pressure, formation parameters, BHA parameters, etc.) and adjusts an operating parameter of the APD Device to provide a desired pressure differential. Devices such as an adjustable bypass can be used to control the APD Device.

Abstract: A formation test tool and methods are described that enable sampling and measurements of parameters of fluids contained in a borehole while reducing the time required for taking such samples and measurements and reducing the risk of formation damage due to sampling induced pressure spikes. The tool has a quick response control system for controlling a fluid transfer device in response to fluid pressure near a sampling port.