Klaas Koster

Time-lapse seismic surveys in the North Sea and their business impact

In a time-lapse 3-D seismic (TL3D) project, a “monitor” seismic survey is compared to a “base” survey. Ideally, the base survey is a 3-D data set acquired before production from the field started. Normally, the monitor survey is acquired after several years of production. The observed differences between the base and the monitor survey can be interpreted in terms of changes in fluid saturation and pressure. When embarking on a seismic monitoring project, it is important to keep the following questions in mind: In this article, we will answer these questions and illustrate our solutions with two examples. ### What field information might technically be obtained? Fluid drainage information from TL3D may be used directly to locate fluid fronts in each major flow unit. It may also be used to derive lateral variations in permeability of the reservoir and sealing capacity of faults. These variations can cause areas of bypassed oil and blocks that are not being drained. In general, it will help to understand the observed production from the field. It is a very powerful method to map production-related changes in reservoir fluid saturation and pressure away from the wells. TL3D very often reveals some flow behavior that had not been predicted, even by history-matched flow models. This information can be critical to future reservoir development. ### What impact will it have on reservoir management? Time-lapse seismic may be used to optimize the number and location of infill wells to access untapped reserves or to accelerate production. Ideally, this will minimize infill costs and maximize recovery. It may also indicate the need to shut off thief zones to avoid premature water or gas breakthrough. It will …

Monitoring primary depletion reservoirs using amplitudes and time shifts from high-repeat seismic surveys

In the high-porosity, poorly consolidated turbidites of the deepwater Gulf of Mexico, production-induced compaction is the main production-drive mechanism when aquifer support is weak and prior to pressure support by secondary recovery water injection. Time-lapse (4D) seismic monitoring of this class of reservoirs has provided several new learning opportunities. The time-lapse amplitude response of these fields can be complicated due to saturation changes (water replacing oil) inside the reservoir, rock compaction causing density and velocity changes inside the reservoir, stress relief and associated deformation of the rock outside the reservoir, and changes in reservoir fluid pressures due to pore-pressure decrease. Methods that rely on time-lapse amplitude changes with offset to discriminate pressure and saturation changes can help separate and thus simplify the interpretation of some of these effects (Tura and Lumley, 1999; Landro, 2001).

Governance reform: Where do we go from here?

The proposal to bring reform of the Societys governance structure to a vote of Active Members was narrowly defeated in the Council meeting during the SEG International Exposition and 80th Annual Meeting. The magnitude of the proposed changes has resulted in some misunderstanding of the overall purpose of the initiative. In addition, many members are undoubtedly interested in the forward-moving plan. I will attempt here to provide clarity, starting with these points: •The effort to bring governance reform to a vote included three years of study and development by the SEG Constitution and Bylaws Strategic Governance Review Committee, led initially by me and more recently by Joe Reilly. The committee engaged Council members and other Society leaders throughout this time before bringing forward a proposal for new Bylaws to replace the current SEG Constitution and Bylaws. The SEG Executive Committee endorsed the proposal before submitting it to the Council. •A majority of Council members attending the meeting...

Introduction to this special section—OTC .08

Starting 5 May and continuing through 8 May 2008, SEG members have the opportunity to participate in OTC .08.

Introduction to this special section Offshore Technology Conference and wide-azimuth seismic acquisition

From 3–6 May 2010, SEG will again cosponsor the Offshore Technology Conference, also known as OTC.10, the worlds foremost event for the development of offshore resources in the fields of drilling, exploration, production, and environmental protection. OTC, founded in 1969, is now held annually at Reliant Center in Houston.

Monitoring Primary-Depletion Reservoirs With Seismic Amplitudes and Time Shifts

In the high-porosity, poorly consolidated turbidites of the deepwater Gulf of Mexico (GOM), production-induced compaction can be the drive mechanism when aquifer support is weak and before pressure support by secondary-recovery water injection begins. Time-lapse (4D) seismic-monitoring time shifts occur in areas of depletion and in the overburden, and they indicate compartmentalization in the reservoir. Compartmentalization information can help place new production and injection wells better, as well as new sidetracks for optimized field development.