Seismic Survey

Sedimentary rock is a type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, mass movement or glaciers.

A proposed 1.5 ha industrial estate overlayed 1.5 - 2.0 metres of uncontrolled fill. The site had been left undeveloped for many years due to the problematic ground conditions. The challenge was to engineer the site such that an allowable bearing capacity of 100 kPa was achieved, in order to render the site suitable for development.

Ground improvement using impact rolling was adopted. After initial impact rolling, seismic methods were used to obtain an indication of the nature of the subsoil by non intrusive methods. Traditional intrusive methods alone and reliance on a method specification were considered too risky given the nature of the fill material.

A Multi-channel Analysis of Surface Waves (MASW) seismic survey was adopted, enabling near surface anomalies to be identified and correlations of seismic velocity with Young’s Modulus to be determined. The seismic survey results generally gave good correlation with traditional geotechnical investigation methods that were also undertaken, and enabled deficient areas to be identified and reworked or excavated and replaced.

The ground improvement proved successful in achieving the required 100 kPa bearing capacity.

Reflection Seismology technique (Seismic Survey) is widely used around the world to produce a detailed analogue image of subsurface geological structures. This information is used by petroleum experts to accurately plan the location of oil wells. Seismic survey sections and corresponding well logs exhibit different variables like acoustic impedance of rock, seismic velocity, rock density, porosity, time and depth that can be manipulated in GIS to infer a subsurface model for stratigraphic as well as structural interpretations. In recent years, GIS has emerged as a powerful analytical tool for subsurface mapping and analysis. Petroleum exploration is a map intensive process that requires the powerful capabilities of GIS. Purpose of this research is integration of Geographical Information System with Seismic Surveys for Structural and Stratigraphic Interpretation of subsurface Geology and locating Petroleum Prospects. In this research work, GIS has been used to investigate subsurface geological structures and stratigraphy to carefully analyze the capabilities of GIS for finding new petroleum prospects in active thrust belt of Meyal, Potwar region, Pakistan. Acquisition of two-dip and three-strike seismic lines is along with well log data, followed by spatial seismic data processing, development of geophysical data management interface, interpolation of shot point data, trend surface analysis and Geostatis-tical analysis using GIS. Subsurface zones of high, low or null probability of petroleum accumulation were then, mapped. Finally, GIS based maps were developed. Geospatial tomography GIS model inferred that study area is structurally deformed and exhibits excessive geological faults, and structural traps. With GIS-tomography interpretation of section 97-MYL-08, a potential oil bearing zone (popup anticline), bounded by two thrust faults was observed at almost 3.6 Km depth in Meyal area How to cite this paper: Fayyaz Z. Fayyaz et al. 1346 with average density of about 2.6 gm/cm 3. Thrust fault recognized from sharp dis-continuity in GIS based survey raster was encountered at 2.9 Km depth. Structure contour map was developed. It depicted that Chorgali formation (dolomitic limestone) at 3.68 Km depth was proven to be reservoir rock in study area. GIS has proved to be a powerful and efficient subsurface modeling and analytical tool and it should be integrated with survey based studies for exploration of oil and gas and investigation of subsurface geological structures.