Abstract: A method and apparatus for measuring the caliber of a borehole while drilling utilizes a borehole compensated downhole measuring system in both a compensated and a non-compensated manner. A transmitter of the measuring system generates a signal which is received by at least one spaced receiver with the time/phase relationship of the transmission and reception of the signal at each receiver being indicative of the borehole caliber.

Abstract: A method and apparatus for determining true formation porosity utilize downhole measurement-while-drilling neutron porosity measurement devices. A initial measurement is taken shortly after the formation is bored and before any substantial invasion by the drilling fluid occurs. Subsequent measurements are made until a steady, no longer increasing, measurement is reached indicating saturation of the formation by the drilling fluid to the depth of the measurements. The steady measurement is indicative of the true porosity of a gas containing formation while the difference between the initial and steady measurements is indicative of the gas saturation of a gas containing formation.

Abstract: The inclination and slope of a bedding plane are determined from oriented measurements of the bending moment generated as a bit encounters and passes completely through the interface between two dissimilar formations. These moments are distinguishable from moments generated by gravity, interaction of the bit and the formation, and interaction of the drill string with the borehole. Preferably, determination of the bedding slope and direction is accomplished by downhole data processing.

Abstract: A system for controlling the direction of a drill bit in a borehole utilizes both a drill string model and a bit-rock directional interaction model to compare ideal predicted or expected moments with real time measured moments to arrive at correction data necessary to return the bit to its desired path. The magnitude and direction of moments generated near the bit are measured in a downhole equipment sub, containing a microprocessor and memory, so that the real time data can be collected and acted upon without undue delay thereby minimizing drilling time lost due to deviations from the desired path.

Abstract: The present invention is directed to an apparatus and method for estimating the value of a parameter of the formation face being penetrated by the drill bit in a drilling operation. The present invention is particularly useful for providing real-time, contemporaneous data concerning the formation face being penetrated for use by the drilling operator or geologist in modifying the drilling operation. The present invention provides a system for estimating the value of one or more parameters of the formation face being penetrated by measuring-while-penetrating one or more measurable parameters of the formation face being penetrated and comparing these values to a data base comprising sets of correlated values for formation parameters of other borehole locations, each set comprising at least a value of the measured parameter and of the parameter of interest.

Abstract: The present invention is directed to a method for determining the stress at the borehole boundary at a selected location within a borehole. The present invention comprises a method for determining the stress employing a plurality of mechanical properties of the formation, e.g., Poisson's Ratio, the rock strength properties and the elastic modulus, together with the measured deformation of the deformed borehole at the selected location. The method comprises measuring at the selected location a plurality of parameters indicative of the formation at that location and from which a plurality of mechanical properties of the formation, e.g., the rock strength properties, the elastic modulus and Poisson's Ratio are determinable, calipering the borehole at the selected location to determine the deformation of the deformed borehole and determining the stress at the borehole boundary at the selected location employing the information obtained by measuring and calipering.

Abstract: Method and apparatus are provided for determining the formation pressure. The magnitude of formation pressure may be derived as a function of changes in bottomhole pressure following swabbing the borehole to draw formation fluids into the borehole, monitoring the borehole for influx of formation fluids, determining the reduced pressure due to swabbing, repeating the swabbing and monitoring steps until an influx of formation fluids is detected thereby determining the pressure of the formation.

Abstract: The present invention is directed to a method for optimizing the tripping velocity of a drill string. The method of the present invention comprises determining the hydraulic fluid pressure in the borehole in a plurality of intervals as the drill string is pulled out of or run into the borehole. These actual pressures are compared against a predetermined acceptable pressure range for each interval. The limits for this acceptable pressure range are set by the maximum acceptable surge pressures and the minimum acceptable swab pressures established for the interval. The velocity of the drill string in each such interval is then adjusted in order to maximize the tripping velocity while maintaining the hydraulic fluid pressure within the acceptable range for each interval.