Abstract: The present invention is directed toward the determination of moisture content per unit volume of material penetrated by a gas filled borehole. An alternate application of the invention is the detection of fractures and vugular cavities in the immediate vicinity of a liquid filled borehole. The apparatus comprises a probe which is conveyed along the borehole. The probe contains a source of neutrons and an epithermal neutron detector at essentially zero longitudinal spacing from the neutron source along the axis of the borehole. In the preferred embodiment, the neutron source is Californium-252 and the epithermal neutron detector comprises a glass scintillator. The response of the system is independent of the thermal neutron absorption properties of the material and the fluid within the borehole.

Abstract: A method for measuring the linear flow velocity, radial position, direction, and the flow rate of water flowing within and behind a well borehole casing. A logging tool containing a source of essentially monoenergetic 14 MeV neutrons and at least one gamma ray detector is positioned within the well borehole opposite the zone in which water flow measurements are desired. The neutron source is turned on thereby irradiating any flowing water and other areas in the vicinity of the well borehole with high energy neutrons. After a predetermined irradiation time, the neutron source is turned off. Following a quiescent period of several milliseconds to allow thermal capture gamma radiation to decay to a negligible level, the gamma ray detector is turned on and the count rate from the N-16 induced within the flowing water is recorded as a function of time. The linear flow velocity, the Full Width Half Maximum time period, and the total count are determined directly from the resulting count rate curve.

Abstract: Formation fluid flows in earth formations (37) opposite a perforated (40) wellbore (15) zone are measured and monitored by injecting radioactive tracers (50) into the perforations (40), blocking the perforations to retain the tracers (50) in the formation (37), monitoring the apparent decay rates (58) of the injected tracers (50), and then determining the rate at which the tracers are being carrier away by fluid movements in the formation (37). From this the flow rate (60) of the fluids in the earth formations (37) adjacent the borehole interval is inferred.

Abstract: A fluid flow and simultaneous fluid density measuring device is set forth. The preferred embodiment incorporates a sonde having a lower inlet port, an upper outlet port, a lengthwise tube extending through the sonde and connected with the ports. A packer provides external isolation to direct all fluid flow into the tube. A float within the tube is buoyantly raised primarily as a function of fluid velocity and fluid density, and the position of the float is measured by placing a radioactive source in the float and measuring the count rate at spaced detectors to ascertain float location. Fluid is simultaneously measured by determining the radiation count rate attenuation of the fluid. With other fixed parameters and measurement of the float position and fluid density, the fluid flow rate can be determined. Both method and apparatus are set forth.

Abstract: A tracer injection method is set forth and is practiced by using spaced end located injectors on a sonde having spaced detectors along the length of the sonde. The injectors inject radioactive isotopes which are distinguishable from one another at the detectors. The method contemplates simultaneous injection of different isotopes, making measurements to determine fluid flow velocity in the casing, and selecting peaks to obtain measurements of the fluid flow velocity in leaks through the casing into external channels along the casing.

Abstract: A method and apparatus (43) are disclosed for natural gamma ray spectral logging of a well borehole (41) to determine the abundances of uranium (U), potassium (K), and thorium (Th) gamma rays in the earth formations (46) adjacent to the borehole (41), and for compensating for borehole attenuation effects upon such gamma photons caused by scattering and absorption phenomena in the materials (42) within the borehole.

Abstract: The disclosure relates to a method and apparatus for logging a borehole. A sonde having a source of penetrating radiation and at least two longitudinally-spaced radiation detectors is passed within a borehole. Count rate data is produced by each of the detectors and is continuously compared to predetermined count rate relationships which may be obtained from detectors operating in reference standard boreholes. In accordance with this count rate data comparison, the suitability of either the "ratio" or "spine/rib" analytical method is determined and the appropriate technique is automatically applied to produce an indication of a logged parameter such as formation porosity, selectively compensated for a borehole environmental condition such as variations in borehole diameter.

Abstract: A multi-function compensated spectral natural gamma ray logging method provides for determining formation and borehole characteristics directly from naturally occurring formation radiation. The method, which measures formation lithology in open holes and mean casing thickness in cased wells, incorporates active compensation for differences in borehole conditions when calculating relative elemental formation abundancies or concentrations of potassium (K), uranium (U) and thorium (T).

Abstract: The disclosure relates to a well logging method which is capable of providing an indication of salinity and water fraction of the production fluid of a borehole. This indication of borehole parameters may be obtained through the use of a conventional gamma ray logging system that detects gamma rays produced by isotopes created from neutron activation of oxygen, sodium, and chlorine that may be present in the production fluid. A logging sonde is passed twice through a portion of interest in the borehole at two different logging speeds. The fluid velocity relative to the sonde may be determined using these two logging speeds and a displacement distance which reflects the time required for a detector associated with the sonde to reach fluid activated by neutrons produced by the sonde.

Abstract: A method for measuring formation density is disclosed. It provides a corrected gamma gamma-type density log having a correction for the adverse effects of gamma radiation from thorium, uranium and potassium ore bodies. The adjacent formation is irradiated with gamma radiation preferably from a cesium (Cs.sup.137) source which emits gamma radiation at 0.663 Mev. Two differently longitudinally spaced detectors are used, a short spaced detector and a long spaced detector. A gamma ray spectrum observed at one of the detectors is broken down into four energy windows across the spectrum and count rate signals are determined and corrected to separate the naturally occurring gamma radiation from the scattered gamma radiation. This information may then be combined with count rate information from the other detector, thereby yielding a compensated density log corrected from naturally occurring gamma rays.

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 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: In the preferred and illustrated embodiment taught herein, method steps for monitoring of raw materials to be used in drilling mud are disclosed. The materials are monitored for radioactivity. Procedures for taking such measurements are disclosed, and the extent of gamma radioactivity in the raw materials used in drilling mud is determined. This is correlated to the increased radiation attributable to mud made from these materials and the effect the mud would have on gamma ray measuring logs. An alternate procedure for testing drilling mud, typically at the well site, is also disclosed. The method detects mud radioactivity from any additives including barite, potassium chloride, well cuttings or others. Excessive background levels due to mud gamma radioactivity in a well may very well mask the data obtained by various logging procedures dependent on gamma radiation. Procedures are also described for either rejecting mud which is too radioactive or correcting the log measurements for mud effects.

Abstract: A method of well logging utilizing naturally occurring gamma radiation is disclosed. In the preferred and illustrated embodiment, the thickness of the casing in a well borehole is measured. The photoelectric absorption of gamma rays from the formation by the iron in the casing varies as a function of the energy of the gamma radiation. The detected gamma spectrum below about 350 KeV from the surrounding earth formation is preferably divided into two energy ranges or windows, and a ratio between the two to indicate the thickness of any intervening steel casing material. With suitable scale factors in calibration of the system, casing thickness can be determined from the ratio of the summed naturally occurring gamma count rate in the range of about 35 to about 120 KeV divided by the count rate in a higher energy range from about 180-325 KeV.

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.

Abstract: A method of logging earth formations to ascertain relative elemental abundancies of potassium (K), uranium (U) and thorium (T) is disclosed. A natural gamma ray spectrum of an unknown borehole is compared with individual standard gamma ray spectra of potassium, uranium and thorium in at least four energy ranges or bands. Decay peaks of the three elements are encompassed by three of the energy bands and at least one other energy band is used to monitor the changes in shape of the unknown spectrum caused by borehole conditions differing from that of the standard or calibration boreholes. A function derived from the gamma ray count rates in the four bands is used to compensate the elemental abundancies of the three elements to be detected in the unknown spectrum for the effects of differing borehole conditions in the unknown borehole from the standard borehole conditions.

Abstract: The present invention concerns methods for measuring simultaneously the formation and borehole components of thermal neutron lifetime as decay time. The borehole and formation are irradiated with pulsed 14 MEV neutrons. During the interval between neutron pulses the capture gamma radiation is measured in at least four, non-overlapping, contiguous time gates. A background radiation measurement is also periodically made. The background corrected capture gamma radiation measurements are combined to derive simultaneously, the formation and borehole neutron lifetime components which are then recorded as a function of borehole depth.

Abstract: Fluid containing free gas and in a pipeline or container at a refinery or at any of various petroleum producing operations is bombarded with neutrons and high energy gamma rays resulting from capture of thermal neutrons are detected. The spectra of the detected gamma rays are then analyzed to determine the concentration of the elements chlorine and hydrogen. The counting rate for thermal neutron gamma rays for hydrogen permits a measure of the hydrogen index (HI) of the fluid to be obtained. The hydrogen index and the relative concentrations of chlorine and hydrogen are used to obtain an indication of the presence and concentration of chlorine or salt water in the fluid.

Abstract: The salt content of a fluid in a pipeline or container in petroleum producing or refining operations is determined by obtaining a measure of water cut of an oil-water-free gas fluid mixture. The conductivity of the fluid is measured by radio frequency (RF) induction techniques, while the density of the fluid is measured and related to the liquid phase fraction of the fluid using gamma radiation techniques. The conductivity and liquid phase fraction are then used to determine salt content of the liquid phase.

Abstract: A method for simultaneously measuring the formation bulk density and the thickness of casing in a cased well borehole is disclosed. Low energy gamma rays are emitted into the casing and formation in a cased borehole. Two longitudinally spaced detectors detect gamma rays scattered back into the borehole by the casing and surrounding earth materials. The count rate signals from the two detectors are appropriately combined according to predetermined relationships to produce the formation bulk density and the casing thickness, which are recorded as a function of borehole depth.