Abstract: A leash is provided for securing tools to a relatively fixed member to ensure against free fall of the tools in the event that they are dropped by a workman. Spring clips at the ends of the leash have arms that interlock, and respectively are receivable within an aperture in a tool and in clamping engagement around the periphery of a pole, tool, or other member, in order to tether the tool to a member capable of retaining the tool in the event of free fall of the tool.

Abstract: A portable uranium analyzer employs a neutron source and a neutron detector for carrying out an uranium assay along the surface of the earth and a gamma ray detector for carrying out a natural gamma radiation assay along the surface of the earth. The neutron source irradiates the underlying earth formation along an exploration line in either a continuous scan mode or in a plurality of fixed assay points. Prompt or delayed neutrons resulting from neutron fission of any uranium present in the formation are detected and recorded during assaying. The uranium assay and the natural gamma radiation assay are correlated to identify formations suspected of containing uranium.

Abstract: A subsurface formation surrounding a borehole is flushed with at least one fluid having a density difference from that of the water content of the formation. Borehole gravity logs are recorded. Porosity is also recorded. From the density, gravity and porosity indications, water and oil saturation of the formation is determined.

Abstract: Novel acoustic logging tools are disclosed for logging unconsolidated formations. These tools include point force shear wave, and multidirectional compressional wave transmitters. A plurality of receivers with sensitivities matched to these transmitter types are provided for selectively gathering P wave and S wave information. The transmitters and receivers are located, sequenced and gated to ensure that high quality wave data is rapidly and reliably collected.

Abstract: A method of open borehole logging is disclosed which provides a mud filtrate penetration index which is proportional to the degree of mud filtrate invasion causing residual oil removal from the vicinity immediately surrounding the borehole. The present invention utilizes a unique combination of formation density logging, dielectric constant logging and gravity meter measurement techniques to arrive at this mud filtrate penetration index, which may also be used to evaluate the probable reliability of residual oil determinations made by these or other logging techniques.

Abstract: A system for assaying for neutron-fission-producing ore in the formations traversed by a borehole includes a pulsed neutron source and a neutron detector. The source is operated to irradiate such ore-bearing formations with fast neutrons, and the detector responds to the delayed fission neutrons emitted by the ore as a measure of ore concentration. The source is also operated to irradiate nonneutron-fission-producing ore-bearing formations with fast neutrons, and the detector responds to the delayed neutrons from oxygen-17 as a measure of the neutron output of the source. The measurement of ore concentration is corrected in accordance with the measured changes in the neutron output of the source.

Abstract: The specification discloses a technique for assaying for delayed fission neutrons from uranium to obtain a quantitative measure of uranium ore grade. In one embodiment, a pulsed neutron source of 14-Mev neutrons and a neutron detector are located in a borehole at the level of a formation of interest. The source is operated cyclically to irradiate the formations with bursts of fast neutrons, and the resulting neutrons from the formations are detected. Measurements are made of those neutrons detected between neutron bursts and indicative of delayed neutrons emitted as a result of neutron fission of uranium. Measurements also are obtained in a nonore-bearing formation to record the count of delayed neutrons emitted from oxygen when irradiated. These measurements are compared with those obtained in the ore-bearing formations of interest to correct for the effect of the oxygen background.