51
Sheppard Michael C, Wick Christian: Method for investigating drag and torque loss in the drilling process.. Anadrill Int, April 13, 1988: EP0263644-A2 (9 worldwide citation)

Drilling conditions are analyzed by, for example, measuring the torque (37) applied at the surface to the drill string (11) and the effective torque (20) acting on the drill bit (14). The applied torque and effective torque are compared to determine torque loss. Likewise, applied weight on the drill ...


52
Clark Brian, Wu Peter T, Grijalva Victor E: Well logging apparatus and method with borehole compensation. Anadrill Int, Schlumberger Services Petrol, June 5, 1996: EP0715188-A2 (9 worldwide citation)

A well logging apparatus and technique for measuring formation resistivity is disclosed which provides advantages of borehole compensation without the requirement of having, for each transmitter to receiver pair spacing, an "equal and opposite" transmitter with the same spacing on the other side of ...


53
Ohmer Herve: Method and apparatus for locating indexing systems in a cased well and conducting multilateral branch operations. Anadrill Int, Schlumberger Services Petrol, October 21, 1998: EP0872626-A2 (8 worldwide citation)

A method and apparatus for positioning and accurately orienting well service equipment within a well casing having an indexing coupling therein to permit the conduct of selected well service operations. A well logging sonde including an ultrasonic scanner system is run into the well casing and, in a ...


54
Rasmus John C: Method and apparatus for determining drilling conditions. Anadrill Int, Schlumberger Services Petrol, May 1, 1996: EP0709546-A2 (8 worldwide citation)

In drilling a well, a condition at the surface which contributes to a downhole condition is identified. A set of observed measurements is collected for the surface and downhole conditions. From this set of observations a predictor equation is derived which expresses the downhole condition as a funct ...


55
Seydoux Jean P, Tabanou Jacques R: Method and apparatus for measuring resistivity of an earth formation. Anadrill Int, Schlumberger Services Petrol, March 24, 1999: EP0903591-A2 (8 worldwide citation)

The method and apparatus of the invention determines earth formation resistivity at extended depths into the formation by the use of telemetry transmission signals to measure the formation resistivity. The telemetry transmission signals carry measurement data from downhole sensors (78) through the f ...


56
Schaaf Stuart, Seydoux Jean, Thain Walter, Wernig Marcus, Dorel Alain: An apparatus and system for making at-bit measurements while drilling. Anadrill Int, Schlumberger Services Petrol, March 10, 1999: EP0900917-A1 (8 worldwide citation)

The system of the present invention includes measurement instrumentation that is located in or near the drill bit and used in a measuring-while-drilling system. The instrumentation can be located in a bit box, an extended sub between the bit box and drilling motor assembly or in the drill bit. The d ...


57
Sheppard Michael, Hedayati Zhian: Method for improving a drilling process by characterizing the hydraulics of the drilling system.. Anadrill Int, Schlumberger Prospection, September 12, 1990: EP0386810-A2 (7 worldwide citation)

A variety of flow and pressure measurements are obtained to characterize the drilling fluids hydraulics system of the borehole drilling process. Notably, a differential pressure measurement which measures the difference between the pressure internal to and external of the drill bit is made close to ...


58
Booer Anthony Kevin: Determination of drill bit rate of penetration from surface measurements.. Anadrill Int, September 1, 1993: GB2264562-A (7 worldwide citation)

A method of determining the rate of penetration DELTA d of a drill bit at the end of a drill string while drilling a well, comprising: (a) measuring the vertical displacement S of the drill string at the surface, (b) determining a state space description of S comprising a state space measurement equ ...


59
David Curry, Michael Sheppard: Method of determining the porosity of an underground formation being drilled. Anadrill, John J Ryberg, Henri Dupont, Stephen L Borst, January 1, 1991: US04981036 (6 worldwide citation)

The invention relates to a method of determining the porosity of an undergound formation being drilled by a rotating drill bit mounted at the lower end of a drill string. The torque (TOR) and the weight (WOB) applied on the bit when drilling the underground formation are measured; the effect of the ...


60
Malone David: Transmitting data at different frequencies in a logging while drilling tool.. Anadrill Int, Schlumberger Services Petrol, March 23, 1994: EP0588390-A1 (6 worldwide citation)

A LWD tool is disclosed comprising, a stator (150), a rotor (160) which rotates relative to the stator (150) thereby effecting a signal in the borehole fluid flowing therethrough, a brushless DC motor (100) coupled to the rotor (160) for driving the rotor, a position sensor (110) coupled to the moto ...