HR: 11:20h
AN: NG32A-04 INVITED     [Abstracts]
TI: Active Geophysical Monitoring in Oil and Gas Industry
AU: * Bakulin, A
EM: Andrey.Bakulin@shell.com
AF: Shell E & P, 3737 Bellaire Blvd, Houston, TX 77025 United States
AU: Calvert, R
EM: rodney.calvert@shell.com
AF: Shell E & P, 3737 Bellaire Blvd, Houston, TX 77025 United States
AB: Effective reservoir management is a Holy Grail of the oil and gas industry. Quest for new technologies is never ending but most often they increase effectiveness and decrease the costs. None of the newcomers proved to be a silver bullet in such a key metric of the industry as average oil recovery factor. This factor is still around 30 %, meaning that 70 % of hydrocarbon reserves are left in the ground in places where we already have expensive infrastructure (platforms, wells) to extract them. Main reason for this inefficiency is our inability to address realistic reservoir complexity. Most of the time we fail to properly characterize our reservoirs before production. As a matter of fact, one of the most important parameters -- permeability -- can not be mapped from remote geophysical methods. Therefore we always start production blind even though reservoir state before production is the simplest one. Once first oil is produced, we greatly complicate the things and quickly become unable to estimate the state and condition of the reservoir (fluid, pressures, faults etc) or oilfield hardware (wells, platforms, pumps) to make a sound next decision in the chain of reservoir management. Our modeling capabilities are such that if we know true state of the things - we can make incredibly accurate predictions and make extremely efficient decisions. Thus the bottleneck is our inability to properly describe the state of the reservoirs in real time. Industry is starting to recognize active monitoring as an answer to this critical issue. We will highlight industry strides in active geophysical monitoring from well to reservoir scale. It is worth noting that when one says ``monitoring" production technologists think of measuring pressures at the wellhead or at the pump, reservoir engineers think of measuring extracted volumes and pressures, while geophysicist may think of change in elastic properties. We prefer to think of monitoring as to measuring those parameters of the reservoir or producing equipment (say wells), that are needed to make next most critical (read expensive and risky) reservoir management decision for particular field. Time-lapse seismic monitoring has become a major tool of aerial field monitoring locating bypassed oil. We show examples when 4D seismic can map average distribution of fluids and pressures throughout the reservoir as well as highlight major challenges related to non-repeatability and changes in the overburden. 4D seismic is one of many surveillance tools used by oil and gas industry. Often, it may not be economic to monitor production with 4D seismic in onshore fields with closely spaced wells and a lot of surface infrastructure. Other downhole methods become preferential in those circumstances. Finally, in difficult environments with expensive infrastructure, monitoring of that surface and subsurface infrastructure becomes an important industrial task in itself. For instance, in a deep-water field it may be task of monitoring state of the well itself since loosing such well due to failure or sand production, may be very expensive and one may rather prefer slight changes in production strategies rather than loss of several expensive wells. Another similar tasks include monitoring platforms or subsurface pipelines. It is important to realize that with proper monitoring in place we still require many other technologies that can act upon the information obtained and increase oil recovery. However it is clear that all these technologies are rendered useless without proper real-time knowledge of the reservoir state i.e. without monitoring.
DE: 0629 Inverse scattering
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0910 Data processing
DE: 0915 Downhole methods
DE: 7200 SEISMOLOGY
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005