Electrical anisotropy of rock is a key parameter in geophysical research. In this paper, digital rocks were constructed by aligning elliptic grains to create samples with anisotropic pore connectivities. Lattice gas automata are used to research electrical transport properties for revealing the anisotropy and physical meaning of Archie's cementation exponent. Simulated results indicate that the relationship between formation factor and porosity is of anisotropy with the exponent corresponding to the change rate of pore complexity with porosity, instead of pore complexity itself, confirming previous theoretical studies. Besides, the results reveal that anisotropy of pore structure is a main factor leading to the anisotropic relation. Under the effects of fracture, there is a U‐shape transition zone over a range of porosity for anisotropy exponent. Moreover, the simulated data are in good agreement with the laboratory experiments, which can further verify the validity of the results.

Acoustic reflection imaging in boreholes is believed to be a vast improvement in the evaluation of heterogeneous reservoirs. However, only 2D azimuth information of reflectors can be achieved by conventional methods. To obtain 3D information, a new high-resolution adaptive beamforming method has been developed to apply to the borehole environment, using an array acoustic logging tool with azimuthally distributed receivers. Moreover, a migration method based on the Fourier finite difference method is introduced into the beamforming to effectively reduce computational complexity from 3D to 2D and to reduce the effects of noise caused by velocity changes in the vertical and horizontal planes. Resolution analysis of the imaging results indicates that the tool diameter and source frequency are the key factors in increasing the azimuth resolution. Furthermore, increasing the resolution with the new method can help improve the fidelity of reconstructed objects in the reflection image. A comparison of results obtained by the new method and the conventional method with simulation data demonstrates that the new method can achieve a reflection image of high azimuth resolution with extremely noisy signals. Application to field data also found a good agreement between the reflection image and the borehole resistivity image. Therefore, detailed information regarding the azimuth and the radial distance of reflectors to the borehole can be determined in 3D space.

An accurate, nondestructive and economic prospecting technique is of utmost significance to explore petroleum resources in desert, however, the typically used technologies fails to provide direct and non-invasive detection. Here we demonstrated a terahertz (THz) prospecting method for predicting the distribution of oil reservoir by extracting the sands from the surface areas in a desert oilfield. The accuracy of THz prospecting reached to more than 80 percent. The trace organic matters migrating from underground reservoir to surface sands can be detected by THz spectroscopy, which was the mechanism of THz spectroscopy for reservoir exploration. The long-chain alkanes, nitro organics and aromatic compounds were also confirmed by thermogravimetric analysis system coupled with Fourier transform infrared and mass spectroscopy. When the trace organics were decomposed from sands, the THz response was equivalent to that of other sands. Consequently, the petroleum prospecting method on the basis of THz spectroscopy is useful for the improvement and optimization of geophysical exploration system in desert.

This study demonstrates that oil shale subjected to pyrolysis at 1000 °C strongly absorbs electromagnetic radiation in the terahertz (THz) range. Analyses reveal obvious differences between oil shale samples with and without pyrolysis, as well as between low-middle mature shale and oil shale samples. The electromagnetic absorption effect of oil shale subjected to pyrolysis conditions is demonstrated to be strongly related to its relatively small concentration of pyrite, which progressively yields pyrrhotite and elemental Fe during pyrolysis that facilitates the absorption of THz radiation. Accordingly, oil shale can be used not only as a resource for generating oil, natural gas, and petrochemical products, but the material obtained after processing can also be employed for the absorption of THz radiation as a means of converting incident electromagnetic radiation into heat or other forms of energy, which offers substantial prospects in many engineering and technology applications.