Integration of TFEM, Seismic and Well data to Reduce Uncertainty in the Search for Oil and Gas: Case Study From South Oman
Seismic reflection method is believed to be the most reliable remote sensing technique in hydrocarbon (HC) exploration business. It was initially used to explore structures in sub-surface. Today, the rapid improvement in seismic reflection data acquisition, processing and quantitative interpretation (QI) make it sometimes possible to detect HC filled structures. Unfortunately, in difficult areas like South Oman, where the acquired seismic suffer from near-surface issues and seismic multiples contamination, QI techniques do not appear to be feasible means of detecting HC. In recent years, the Controlled Source Electromagnetic (CSEM) method has become a significant tool for hydrocarbon detection in offshore areas. CSEM includes all electromagnetic geophysical prospecting techniques that use active sources. Like other CSEM methods, the TFEM technique joins the time-domain and frequency-domain of electromagnetic (EM) weaves (He et al., 2002; He, 2003). The TFEM method is an innovation of spectral induced polarisation (SIP), and can be used to directly detect HC. In this study, a project using time frequency electromagnetic (TFEM), shallow EM (TDEM) and magnetotelluric (MT) methods was carried out in the southeast of Oman, in order to verify the effectiveness of the TFEM method in determining the presence of hydrocarbon. A trial was conducted to investigate three scenarios, involving a proven oil-bearing reservoir, a proven water-bearing reservoir and many undrilled prospects. The study location is characterised by noisy seismic data. The presence of near-surface complexity and lack of reliable seismic data motivated the use of joint-geophysical exploration approaches. The study aimed to determine the feasibility of getting sensible TFEM results over the study area, and was executed successfully. It was necessary to overcome shallow high resistive layers by drilling geotechnical wells up to the water table in order to place the electric sources. The TDEM method was used to determine the depth of the top of the water table. Petrophysical, geological and geophysical data integration is crucial to near accurate subsurface models. The constrained TFEM inversion results in this study were correlated with resistivity well logs. There was a match between the direct measurements and remotely sensed TFEM measurements of resistivity. Therefore, it can be concluded that the TFEM trial can help to make exploration activity less risky.
AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014