PROCESSING REGIONAL GRAVITY AND MAGNETIC DATA FOR PETROLEUM RESOURCE ASSESSMENT OF THE CIRCUM ARCTIC

Petroleum resource assessment is a practice undertaken to understand an area's oil and gas resource prospective. This requires knowledge of the total petroleum system; a concept that includes essential geologic elements such as petroleum source, reservoir type, reservoir extent, and the timing of geologic events. Often petroleum resource assessment is accomplished by applying previous knowledge gained from analog petroleum fields throughout the world. Selecting analogs and understanding essential geologic elements uses a variety of scientific methodologies including geophysical techniques.

In frontier locations of the Arctic, geophysical information is generally limited to regional gravity and magnetic data, with few, if any, seismic profiles or logged boreholes. This presentation focuses on processing techniques applied to gravity and magnetic data useful in aiding oil and gas resource assessment. Techniques include image enhancement and geophysical contact detection using pseudo-gravity transforms of magnetic data, terracing, and horizontal gradient methods (horizontal derivative, analytic signal, and local wavenumber), as well as matched-filtering for source-body depth and dip estimation. Where appropriately applied, these processing methods increase the utility of magnetic and gravity data by transforming it into pseudo-geologic images and tables that are more easily interpreted by individuals without extensive training in geophysical methods; hence, facilitating closer interaction between geologists and geophysicists throughout interpretation tasks. Descriptions of the data processing techniques are given along with real-world examples from petroleum provinces north of the Arctic Circle.