Abstract: A method of heating an oil shale formation to produce shale oil includes radiating RF energy into the oil shale formation for a predetermined first time interval from a first borehole which penetrates said oil shale formation. Shale oil is produced when available during said first time interval from a second borehole penetrating said oil shale formation which is a predetermined distance from the first borehole. During a predetermined second time interval, RF energy is again radiated into the oil shale formation from the second borehole while shale oil is produced from the first borehole during the second time interval.

Abstract: A method of monitoring underground processes in which changes of material properties of underground strata occur in a limited area, especially in regard to in-situ combustions, gasifications in coal and petroleum deposits, in order to localize and determine the degree of change of material properties of underground strata, includes emitting exactly reproducible time-sequential seismic signals in each geological strata where changes are expected to take place. The signals are recorded in the appropriate geological stratum at one or more positions, or in the same position. The signals are stacked with signals of reverse sign. The magnitude of the difference signals obtained and their propagation time are determined.

Abstract: A method for measuring the location, linear flow rate, and volume flow rate of undesired water flow behind well casing in a well includes irradiating borehole environs with high energy neutrons from a neutron source located in a well tool in the borehole. Gamma rays from the decay of an unstable isotope which comprises a portion of any undesired behind casing flow present are detected with gamma ray detectors located in the well logging tool. Count signals representative of the detected gamma rays from at least one of the detectors are separated into at least three energy dependent signals. A ratio signal corresponding to the ratio of at least two of the three energy dependent signals is generated and an indication of the linear flow rate of the undesired behind casing water flow in a preferred direction is determined from the count signals from the detectors and from the first predetermined relationship.

Abstract: A method of two dimensional chemical flood testing includes evacuating a porous medium contained in a test cell. The porous medium in the test cell is irradiated with a beam of microwave energy at a plurality of predetermined locations on said test cell. The microwave energy that has passed through the porous medium at each location is detected at the location. The porous medium in the test cell is filled with brine. The irradiating and detecting steps are repeated, the porous medium is then flooded with crude oil, or a substitute, and again the irradiating and detecting steps are repeated. The porous medium is flooded with brine and again the irradiating and detecting steps are repeated. A calibration curve for each location is derived from the detected microwave energy at the location from the prior irradiating and detecting steps.

Abstract: A temperature stabilization system for a radiation detector in a well logging tool includes a temperature sensor which senses the temperature and provides a corresponding signal. Apparatus located within the logging tool and containing the radiation detector provides a controllable temperature environment for the radiation detector. A heat exchanger transfers heat from the apparatus in accordance with the temperature signal so as to stabilize the temperature in the apparatus for the radiation detector. A heat disposing device is arranged with the heat exchanger to dispose of the transferred heat.

Abstract: A system for emitting electromagnetic energy at a radio frequency into a hydrocarbon stratum of earth formation traversed by borehole includes a source having impedance matching capability, which provides electromagnetic energy at a radio frequency, and an applicator which is used to emit the RF energy into the hydrocarbon stratum. The applicator includes an outer conductor and an inner conductor that is substantially longer than the outer conductor. The outer conductor is arranged with the inner conductor in a manner so that a portion of the inner conductor is located within the outer conductor and the portion of the inner conductor not located within the outer conductor is used for emitting the RF energy when the applicator is energized by the source. An end piece affixed to the inner conductor holds a plurality of insulators in place. The insulators are of a type that should they come into contact with the inner conductor substantially no phase shift of the RF energy occurs.

Abstract: A petroleum stream analyzer includes a test cell having a petroleum stream, or portion thereof, flowing through it. A neutron source bombards the petroleum stream in the test cell with fast neutrons, which are slowed down and thereafter engaged in thermal neutron capture reaction with materials in the petroleum stream. Gamma ray apparatus including a gamma ray detector provides an energy spectra of gamma rays from the materials in response to the capture of the thermal neutrons by the materials in the petroleum stream. Shielding material separates the neutron source from the gamma ray detector and a housing located within the test cell houses the neutron source, the gamma ray detector and the shielding material in a manner so that a longitudinal axis of the housing, which is substantially aligned with the axial flow of the petroleum stream in the test cell, passes through the neutron source, the shielding material and the gamma ray detector.

Abstract: Formations adjacent a well borehole are activated with neutrons from a pulsed neutron source in a sonde at an energy level, such as 14 MeV, to energize oxygen present in the formation and borehole, giving rise to gamma radiation from O.sup.16 (n,p)N.sup.16 reaction. Gamma radiation in the energy windows 3.25-4.00 MeV and 4.75-7.20 MeV is detected in a time gated detector and counted. Count rate contributions from the borehole and from the formation are differentiated on the basis of radial distance from the center of the sonde. In this manner, compensation for adverse effects of borehole oxygen activation on formation oxygen activation measurements of interest is achieved. Further, the neutron output intensity of the pulse neutron source may also be measured.

Abstract: A water cut monitor includes a microwave transmitter which transmits microwave energy through a fluid mixture containing water. An indicator connected to the microwave transmitter and receiving the microwave energy transmitted through the emulsion provides an indication of the water fraction of the fluid mixture in accordance with the phase difference between the microwave energy from the transmitter means and the microwave energy transmitted through the fluid mixture.

Abstract: A method of determining the permeability of a particular stratum in an earth formation traversed by a borehole includes injecting a liquid into the borehole at a first pressure thereby causing liquid flow into the stratum. A first flow rate of the liquid is determined at the first pressure. The pressure of the liquid being injected into the borehole is then changed to a second pressure level and a second flow rate of the liquid flowing into the stratum is determined at the second pressure. An indication of the permeability of the stratum is then derived in accordance with the two pressures, the two flow rates and known characteristics of the stratum.

Abstract: This invention relates to an improved method for determining the oil saturation of subsurface earth formations in the vicinity of a well borehole. High energy neutrons irradiate the subsurface earth formations and gamma rays caused by inelastic scatter with the subsurface earth formation constituent materials are measured. For a chosen borehole depth, gamma ray logs are taken in different situations: first, with the formation fluid water and oil mixture in an undisturbed state; second, after flushing the formation with alcohol to displace the formation water and oil mixture; and, finally, after flushing the alcohol from the formation with water to obtain a measurement with no oil in the formation. The gamma ray measurements obtained are then used to determine the oil saturation without requiring knowledge of the porosity of the earth formation, borehole conditions or formation type.

Abstract: A microwave core monitor includes a sample cell which contains a test core of an earth formation. A microwave transmitter irradiates the test core with a beam of electromagnetic energy at a microwave frequency. A microwave receiver provides an indication representative of a characteristic of a liquid, or the absence of a liquid, in the test core in accordance with electromagnetic energy that has passed through the core. The sample cell further includes microwave absorber rods which prevent portions of the beam of electromagnetic energy not passing through the test core from reaching the receiver.

Abstract: A paraffin monitor apparatus responsive to changes in resistance includes a plurality of paraffin sensing means which are placed in a liquid medium containing paraffin. The paraffin sensing means are housed in a non-metallic, hard material having a plurality of channels so that each paraffin sensing means has at least one surface substantially in conformity to a surface of the non-metallic, hard material. A predetermined length of tubing is affixed to the non-metallic, hard material, and a plurality of wires, each of which passes through a channel of the non-metallic, hard material and the tubing, connect with corresponding paraffin sensing means. An adapter affixed to the tubing permits insertion of the non-metallic, hard material and a portion of the tubing into a pipeline containing a flowing liquid medium having paraffin.

Abstract: An improved radioactivity well logging sonde for sensing fluid flow in an earthen formation from a borehole traversing the formation in which the borehole also contains salt water includes a neutron source for irradiating the earthen formation with neutrons and a detector assembly which detects gamma radiation from the earth formation. The sonde also includes circuitry which processes pulses from the detector assembly to be provided uphole by way of a well logging cable. The sonde includes apparatus spatially arranged with the detector assembly which displaces salt water in the borehole so that there is substantially no salt water between the side of the borehole and the detector assembly. The improved well logging sonde also permits vertical fluid flow measurements in an earthen formation as well as the conventional horizontal fluid flow.

Abstract: A method of determining the oil and water relative permeabilities and the water saturation of a core of earthen material which includes providing a two phase oil/water liquid to and through said core. The core is irradiated with microwave energy while the liquid is in the core. A received energy signal is generated in accordance with the microwave energy that has passed through the core. A liquid pressure drop along a predetermined length of said core is sensed and a representative pressure drop signal is provided. The oil and water relative permeabilities and the water saturation of the core are derived in accordance with the flow rate of the liquid, the received energy signal and the pressure drop signal. The liquid flow rate may be either sensed or the liquid may be provided at a predetermined flow rate.

Abstract: A method of testing a chemical for use in an enhanced recovery of oil from an earth formation includes obtaining a test core of an earth formation. The test core is cleaned and then subjected to a predetermined sequence of events similar to that which the reservoir has experienced. The test core is flooded with a chemical to be tested and the chemical is then driven from the test core with a drive liquid. The test core is irradiated with a beam of electromagnetic energy at a microwave frequency. An indication representative of the effectiveness of the chemical in the test core is derived in accordance with the electromagnetic energy that has passed through the test core.

Abstract: A method, when practiced, enhances seismic data so as to suppress noise in the seismic data. The seismic data was generated in a conventional manner by at least one receiver apparatus whose position does not substantially change. The method includes combining at least two elementary seismograms to form noise seismograms containing little or none of the desired signal. The number of different noise seismograms so derived is at least equal to the number of elementary seismograms to be combined to form a final seismogram. The probability distribution of noise is determined for each trace of the noise seismograms from the probability distributions of noise in the traces of the noise seismograms. The most probable form of the desired signals is derived from the probability distribution of noise in the traces of the elementary seismograms to provide the enhanced seismic data.

Abstract: A crude oil production stream analyzer includes a device which measures the dielectric constant of the crude oil production stream and provides a signal corresponding thereto. A densitometer provides a density signal representative of the density of the crude oil production stream. At least one constituent of the crude oil production stream is determined in accordance with the dielectric constant signal and the density signal and the temperature of the crude oil production stream which is sensed by a temperature sensor.

Abstract: Methods and apparatus are provided for making improved pulsed neutron derived measurements of the carbon: oxygen ratio in subsurface earth formations. Plural radiation measurements are made as a function of time from the initiation of the neutron pulse to distinguish inelastic and thermal neutron interactions. These measurements are then combined in several different manners to provide an improved carbon:oxygen ratio measurement and multiple porosity and formation lithology indication measurements.

Abstract: A natural gamma ray logging system utilizes gamma ray spectroscopy to measure thorium, uranium and potassium content of earth formations adjacent a well borehole. An additional measurement is also taken from which compensation for borehole effects on the measurements of interest is achieved.