Examples of 4D Studies from Kuwait

Introduction The use of the Time Lapse, or 4D, seismic technology is well established in the marine offshore seismic environment, this technology is not so well established yet in the land seismic environment The effectiveness of 4D seismic surveys for monitoring production-induced effects in the reservoir is determined by the magnitude of the change in seismic response and by the repeatability of the seismic experiments over the time periods. KOC has recognized the significance and potential of 4D seismic as a powerful and cost effective tool for reservoir management. KOC also comprehends the need to test and evaluate all available, and the emerging, technologies to make 4D successful. In this paper we review several 4D examples, with emphasize on a repeatability study onshore conducted in North Kuwait and a 4D reservoir study performed in Minagish field; West Kuwait. History of 4D seismic in Kuwait Between 1996 and 1999, during the acquisition of the 2D and 3D seismic surveys across the State of Kuwait, KOC Exploration Group made the decision to evaluate the effectiveness of 4D seismic as a tool for reservoir production monitoring over some of its key producing fields. Four pilot areas were selected over the Minagish, Raudhatain, Sabiriyah and Burgan fields (Figure 1). A small time lapse pilot seismic surveys varying in size from 9 Km² to 50 Km² were acquired and processed. The two pilots with the greatest potential were subsequently re-processed using the latest 4D analysis and processing techniques. In 2004 KOC demonstrated its position at the leading edge of Time Lapse technology by carrying out the first seismic study in the Middle East using single sensor seismic over the 4D pilot area in the Minagish field. The fine spatial sampling obtained by single sensor technology provides highly effective coherent noise attenuation, by attenuating such noise the signal to noise levels of Time Lapse data improved to the point where the subtle changes in acoustic impedance due to fluid changes in the carbonate Minagish Oolite reservoir could be more effectively detected.