Geophysics and Engineering

Perspective

An introduction to geophysical methods should have a look for natural resources and to survey earth's geology is presented during this volume. It is suitable for second-and third-year undergraduate students majoring in geology or engineering and for professional engineering and for professional engineers and earth scientists without formal instruction in geophysics. The author assumes the reader is conversant in geometry, algebra, and trigonometry. Geophysical exploration includes seismic refraction and reflection surveying, electrical resistivity and electromagnetic field surveying, and geophysical well logging. Surveying operations are described in step-by-step procedures and are illustrated by practical examples.

Gravity anomalies provide valuable information about the Earth‘s gravity field. They are used for solving various geophysical and geodetic tasks, mineral and oil exploration, geoid and quasi-geoid determination, geodynamic processes of Earth, determination of the orbits of varied objects, occupation space round the Earth etc. The increasing accuracy of solving the above mentioned problems poses new requirements for the accuracy of the gravity anomalies.

Increasing the accuracy of gravity anomalies are often achieved by gaining the accuracy of the gravimetric and geodetic measurements, and by improving the methodology of the anomalies detection. The fashionable gravimetric devices allow living the gravity with an accuracy of several microgals. Space geodetic systems allow defining the geodetic coordinates and ellipsoidal heights of gravimetric points within a centimeter accuracy. This exposes the new opportunities to calculate in practice both hybrid and pure gravity anomalies and to enhance their accuracy. During this context, it's important to analyse the chances of detecting various gravity anomalies and to enhance the methodology for detecting gravity anomalies. Also it's important the right selection of the gravity anomalies for various geodetic, geophysical and environmental engineering tasks. The fashionable gravity field data of the territory of Lithuania are used for the research.

Optimal upscaling of a high-resolution static geologic model that reflects the flow performance of the reservoir is vital for reasons like time and calculation efficiency. During this study, we demonstrate that honoring reservoir heterogeneity is critical in predicting accurate production and reducing the time and price of running reservoir flow simulations for the Hunton Group carbonate. We integrated three-dimensional (3D) seismic data, well logs, thin sections, outcrops, multiscale fracture studies, discrete fracture networks, and geostatistical methods to make a 100 × 150 × 1 ft gridded representative geologic model. We calibrated our gridded porosity and permeability parameters, including the evaluation of fractures, by history matching the simulated production rate and cumulative production volumes from a baseline fine-scale model generated from petrophysical and production data obtained from five wells. We subsequently reperformed the simulations employing a suite of coarser grids to validate our property upscaling workflow. Compared to our baseline history matching, increasing the horizontal grid cell sizes (i.e., horizontal upscaling) by factors of two , 4, 8, and 16 leads to cumulative production errors starting from +0.5% for 2 time (2×) coarser to +74.22% for 16× coarser. The errors related to vertical upscaling were significantly less, i.e., starting from +0.5% for 2× coarser to +10.8% for 16× coarser. We observed higher production history matching errors related to natural fracture size. Results indicate that greater connectivity provided by natural fracture length features a larger effect on production compared to the upper permeability provided by larger apertures. We also estimated the trade-off between accuracy and run times using two methods: (a) using progressively larger grid cell sizes; (b) applying 1, 5, 10, and 20 parallel processes. Computation time reduction in both scenarios could also be described by simple Stevens' law equations. Observations made up of our case study and upscaling workflow could also be applicable to other carbonate reservoirs.

The extremely low permeability of the many tight formations has required hydraulic and acid fracturing which introduce both geochemical and mechanical alterations to reservoir rock. There is an increasing got to effectively monitor those changes in place for both economic and environmental considerations. We have been conducting engineering geophysics experiments to reinforce the interpretation of hydraulic fracturing by characterizing acoustic velocity of propped and acidified fractures also as acoustic emissions occurring upon chemo-mechanical rock deformation. Our experiments show that P- and S-waves are affected differently, with S-wave velocity being particularly susceptible to geochemically altered and propped fracture zones. Acoustic emission accounts just for a little portion of the entire energy released from rock fracturing process.

The combination of geophysical data and geotechnical measurements may greatly improve the standard of buildings under construction in engineering. A case study is presented here at a vacant lot. Initially, boreholes indicated a posh geology. A dipole-dipole configuration was selected for Electrical Resistivity Tomography (ERT) implementation and therefore the data were processed and interpreted by applying 2D and 3D inversions. An electromagnetic survey was also administered at a special time periods and successfully wont to verify the results of the resistivity measurements. It is demonstrated that engineering geophysics is in a position to supply solutions for determining subsurface properties which different prospection techniques are necessary for developing an inexpensive model of the subsurface structure.