Abstract: An improved tool for controlling the rate of flow of cement into a well to control the consolidation of a formation is disclosed. The tool comprises a housing, an actuator and a valve member, motion of which is controlled by axial motion of the actuator within the housing. In the preferred embodiment, the valve member includes a fixed size choke orifice which controls the flow of cement into the formation. The tool is operated by lowering it into a well with the valve open, fixing the housing to the casing of the well, pumping cement below the valve, lowering the actuator with respect to the housing to close the valve, and pressurizing the well to force the cement into the formation at a rate controlled by the size of the choke orifice.

Abstract: Electrical contact is made between an electrode and a liquid column to establish current flow between the electrode and the liquid column. The electrode is raised up the liquid column until electrical contact is broken. An additional quantity of liquid is added to the liquid column to cause the column to rise and make electrical contact with the electrode. The electrode is raised up the liquid column until electrical contact is again broken. The distance of travel of the electrode is measured as a determination of the rise in height of the liquid column and of the additional volume of liquid added to the column.

Abstract: Apparatus for gravel packing a wellbore interval having shunt means (i.e. conduits) on the external surface of a sand screen which can selectively deliver a gravel slurry to different levels of the interval during operation. The shunt means is comprised of a variety of differently configured, perforated conduits and/or arrangements of these conduits.

Abstract: The maximum correlation between a pair of curves is determined from the maximum value of the common area of such curves with respect to reference lines within a select window as one of the curves is moved through the window while the other of the curves remains fixed within the window.

Abstract: A cylindrical core sample of a subterranean formation is place into a sleeve under confining pressure. At least one electrode array extends through the sleeve and makes contact with the core sample. The array is in a plane normal to the core sample and has an even number of electrodes equally spaced about the sleeve. A current is passed through the core sample and voltages are measured across each pair of electrodes that are spaced 180.degree. apart around the sleeve. Such measurements are utilized to identify the radial direction of any electrical anisotropy in the core sample, particularly under differing fluid saturation conditions.

Abstract: A method and apparatus for laboratory simulation of the dynamic formation of sand arches in production of oil and/or gas from unconsolidated or poorly consolidated wells is disclosed. An ultrasonic transducer is disposed opposite a perforation in a member simulating the casing of a well and the simulated well is operated at conditions approximating those of interest in the field. The acoustic transducer is moved incrementally across the perforation and measurements of the distance between the transducer and the formation are measured. These can then be used to generate a profile of the surface of the formation behind the perforation. Preferably, an ultrasonic transducer which emits a focussed beam of acoustic energy is employed.

Abstract: An improved centralizer for well casing, comprising an externally threaded upper anchor fixed to the casing, an upper collar threaded to the upper anchor, a lower anchor fixed to the casing, a lower collar bearing against said lower anchor, and a plurality of relatively flexible metallic straps extending between the collars. The centralizer is assembled over a section of well casing as the casing is lowered into the well. When the casing reaches its final depth, it is rotated so that the anchors rotate with the casing, while the collars and the straps remain stationary, as the straps engage the wellbore. When the casing is thus rotated, the upper collar moves along the threads of the upper anchor towards the lower collar, axial movement of which is prevented by the lower anchor. This forces the straps to bulge outwardly away from the casing, urging the casing toward the center of the borehole.

Abstract: A transversely isotropic cylindrical core sample of a subterranean formation is fluid saturated and subjected to a confining pressure. Electrical potential is measured along the core sample and in a plurality of direction through the core sample which are normal to the cylindrical axis of the core sample at a plurality of spaced-apart positions along such axis. From these electric potential measurement tensor conductivity components normal to and lying within the bedding plane of the core sample are determined.

Abstract: A cylindrical core sample of a subterranean formation is fluid saturated and subjected to a confining pressure. Voltages are measured in a plurality of directions through the core sample which are normal to the cylindrical axis of the core sample at a plurality of spaced-apart positions along such axis and utilized to determine resistivities. These resistivities are compared to identify the radial direction of any electrical anisotropy in the core sample for differing fluid saturation conditions.

Abstract: A sand screen is positioned in a well adjacent an oil or gas reservoir to be produced. At least one conduit is in juxtaposition with the sand screen and has passageways at selected intervals to establish fluid communication between the conduit and the annulus of the well surrounding the sand screen. A gravel packing slurry is injected down the well to form a gravel pack in the annulus. Actuatable devices associated with the conduit passageways control fluid flow between the conduit and annulus so that if the gravel portion of the slurry forms a bridge in the annulus, thereby blocking slurry flow through the annulus, the slurry will be diverted from the annulus into the conduit through one or more of the passageways in the conduit above the bridge, downward through the conduit and out through one or more passageways in the conduit into the annulus below the bridge to continue the forming of the gravel pack in the annulus.

Abstract: A water-saturated core sample of a porous rock is placed in a sleeve which a hydrophobic membrane in one end and a hydrophilic membrane in a second end. A pressurized hydrocarbon is injected into the core sample through the hydrophobic membrane to displace the water in the core sample whereby it drains through the hydrophilic membrane into a collector. Upon a depressurization of the injected hydrocarbon below the displacement pressure of the hydrophilic membrane, the water imbibes back into the core sample through the hydrophilic membrane. Upon a pressurization of the imbibing water above atmospheric pressure the water displaces the hydrocarbon from the core sample through the hydrophobic membrane.

Abstract: A core sample of a porous rock having a wettability representative of a subterranean formation is saturated with a first medium. This first medium is then displaced with an immiscible second medium. Capillary pressure versus wetting phase saturation is measured during the displacement of the first medium with the second medium within the core sample. Mercury is injected into an evacuated core sample of the porous rock, mercury vapor acting as a wetting phase on the porous rock. Capillary pressure versus wetting phase saturation is measured during mercury injection on the evacuated core sample. The ratio of the two capillary pressure versus wetting phase saturation measurements is determined and taken to be an indicator of the wettability of different size pore throats in the porous rock.

Abstract: A borehole logging tool is lowered into a borehole traversing a subsurface formation and a neutron detector measures the die-away of nuclear radiation in the formation. A model of the die-away of nuclear radiation is produced using exponential terms varying as the sum of borehole, formation and thermal neutron background components. Exponentially weighted moments of both the die-away measurements and die-away model are determined and equated. The equated moments are solved for the ratio of the borehole to formation amplitude components of the measurements. The formation decay constant is determined from at least the formation and thermal neutron background terms of the weighted measurement and model moments. The determined borehole to formation amplitude ratio is used to correct the determined formation decay constant for the effects of detector standoff from the borehole wall.

Abstract: In seismic exploration, seismic reflections from subsurface formations are recorded in the form of a time-distance array of seismic traces. This array is transformed into a frequency-distance domain. Frequencies at which coherent noise resides within the frequency-distance domain are determined. Wavenumbers corresponding to such frequenices are removed by filtering. The wavenumber-filtered, frequency-distance domain of seismic traces are then transformed back into a time-distance array of seismic traces.

Abstract: X-ray attenuation measurements at two or more energies are carried out on core samples of earth materials for use in determining relative Compton scattering and photoelectric contributions to attenuation. The measurements are utilized to calculate material bulk density from the change in attenuation between such dual X-ray energies and the attenuation for one of the dual X-ray energies.

Abstract: A method and apparatus for acquiring acoustical data from a borehole and is especially useful in carrying out tomogrphy surveys. The borehole digital geophone (BDG) tool of the present invention is capable of operating from a standard, 7-conductor logging cable with no special cables being required since the individual digital geophone modules (DGM) which form the BDG tool are connected together by short, separate lengths of the same 7-conductor cable. Each DGM acquires, digitizes, stacks, and stores data generated by its own three-component geophone assembly prior to transmitting these signals to the surface over a dedicated conductor in the cable thereby substantially increasing the sample rate of the tool which, in turn, substantially reduces the field time to run a tomography survey.

Abstract: In seismic exploration, seismic reflection from subsurface formations are recorded in the form of a time-distance of seismic traces. This array is transformed into a time-wavenumber domain. Wavenumbers at which coherent noise resides within the time-wavenumber domain are determined. Frequencies corresponding to such wavenumbers are removed by filtering. The frequency-filtered, time-wavenumber domain of seismic traces are then transformed back into a time-distance array of seismic traces.

Abstract: A method of removing multiple reflection events from seismic records is described. A shallow primary reflection event is used as a model for a deeper primary, and is distorted responsive to the predicted static correction to yield a model for the multiple. The method is applied to common depth point (CDP) records, in which the common-midpoint contribution of the multiple to each CDP record can be assumed to be equal. Preferably, a total least squares correlation step is used to design a convolutional filter applied to the data records to remove the multiples therefrom.

Abstract: A method and apparatus for constructing an ice structure in deep (e.g. 50 feet) waters having a moving sheet of ice on the surface. A rubble generator is positioned in the path of the ice sheet and a portion of the marine bottom is artificially raised adjacent to and on the upstream side of the generator by submerging at least one berm onto the marine bottom. The height of the berm is such that it artificially raise the marine bottom to a depth which is less than the original keel depth of a pile of ice rubble formed when the moving ice sheet interacts with the generator thereby the rubble pile will be spontaneously grounded and immobilized on the berm. Once the rubble pile is grounded, additional ice (e.g. spray-ice) is accumulated thereon to complete the ice structure.

Abstract: An improved method for filtering noise bands from seismic data is described. The data is analyzed to determine the frequency component of the undesired noise, and a precise autocorrelation function is generated and used to design a filter to remove the undesired frequency component from the data. The filter can be band pass, band reject, notch, low pass, or high pass, and multiple bands of noise can be removed from the seismic data in a single filtering operation.