We present a feasibility study for interpretation of gravity gradient surveys in a single borehole using both an analytic and inverse-based approach. We analytically solve for distance and direction angles to a point source using the components of the gravity gradient tensor from a set of observations in a single borehole. We then generalize this approach to include the response due to a prisma...

We present a borehole failure model which is based on fracture mechanics and layer buckling theories and compare its prediction with experimental data. The model assumes that the main mechanism of borehole collapse takes place in the form of layers buckling near the borehole surface. The model introduces a combination of fracture mechanics parameters with dimension of length that scale the size...

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on c...

Knowledge of the orientation of horizontal in situ stresses is important to some areas of oil and gas field development plans. Borehole breakouts observed in image logs and drilling-induced fractures are the main parameters for the determination of the stresses’ directions in situ. In this work, the orientations of borehole breakouts were investigated as a function of depth in oil wells A and ...

The physical samples of natural gas hydrate were obtained first by drilling in permafrost region of Qilian Mountain of China in 2008. Permafrost area in Qilian Mt. is located in lower latitudes at high altitude, and the samples form in the Jurassic stratum under hard rock environment, rather than in unconsolidated soil layer. The environment of the Gas hydrate discovered is different from in th...

Detailed information about the spatial distribution of subsurface properties is important in many fields. One method that can image the seismic velocity structure of the shallow subsurface is crosswell seismic tomography. By including rays traveling from the boreholes to the surface, the angular coverage of crosswell tomograms can be significantly improved. We investigated the effects of these ...

Before embarking on any mining operation, it is advantageous to locate the subsurface orebody in three-dimensions with a high resolution (~1m) ahead of actual mining, because this will increase productivity and efficiency. Borehole radar is such an emerging mapping tool in the mining industry, that can be used to image the subsurface orebody with high resolution. 3-D subsurface imaging using tw...

Borehole radar is an electromagnetic tool that can be applied to assist in the delineation of orebody geometry, ideally using routinely drilled cover and exploration boreholes. Successful trials of borehole radar for delineating reef horizons on South African gold and platinum mines have led to the development of a borehole radar system specifically designed for routine application in those eny...

We have employed a few-parameter estimation (FPE) technique to derive information on past surface temperature variations from present-day borehole temperatures. Synthetic experiments show that the FPE t•hnique can separate reasonably well information on century-long trends of surface temperature change from borehole temperatures within a .wide range of noise levels. The technique also allows a ...