A 3-D seismic case history evaluating fluvially deposited thin‐bed reservoirs in a gas‐producing property

Abstract

We conducted a study at Stratton Field, a large Frio gas‐producing property in Kleberg and Nueces Counties in South Texas, to determine how to best integrate geophysics, geology, and reservoir engineering technologies to detect thin‐bed compartmented reservoirs in a fluvially deposited reservoir system. This study documents that narrow, meandering, channel‐fill reservoirs as thin as 10 ft (3 m) and as narrow as 200 ft (61 m) can be detected with 3-D seismic imaging at depths exceeding 6000 ft (1800 m) if the 3-D data are carefully calibrated using vertical seismic profile (VSP) control. Even though the 3-D seismic images show considerable stratigraphic detail in the interwell spaces and indicate where numerous thin‐bed compartment boundaries could exist, the seismic images cannot by themselves specify which stratigraphic features are the flow barriers that create the reservoir compartmentalization. However, when well production histories, reservoir pressure histories, and pressure interference tests are incorporated into the 3-D seismic interpretation, a compartmentalized model of the reservoir system can be constructed that allows improved development drilling and reservoir management to be implemented. This case history illustrates how realistic, thin‐bed, compartmented reservoir models result when geologists, engineers, and geophysicists work together to develop a unified model of a stratigraphically complex reservoir system.

Deep-water and fluvial sinuous channels—Characteristics, similarities and dissimilarities, and modes of formation

“…Amplitude slices of some fluvial point-bars, presented by Isa et al (1992), Hardage et al (1994), Posamentier (2001), Miall (2002), Carter (2003) and Feldman and Maynard (2005), also exhibit scroll-bar patterns within meander (Wongsosantiko and Wirojudo, 1984). The sinuous channel in the center of the slice shows high seismic-amplitude point-bar scrolls.…”

Location and Felt Reports for the 25 April 2010 mbLg 3.9 Earthquake near Alice, Texas: Was it Induced by Petroleum Production?

“…Some geophysical survey information is in the public domain for the Stratton field (e.g., see Hardage et al, 1994;Levey, Hardage, et al, 1994), but the fact that this is unusual will complicate efforts to make systematic comparative studies with other fields in similar environments.…”

“…8 and Swanson and Karlsen, 2009). There are more than 100 producing reservoirs in the Stratton field; most are sand-rich channel-fill and splay deposits interstratified with floodplain mudstones; because of their fluvial origin, individual reservoirs are typically only 5-10 m thick and all are less than 1-2 km in aerial extent (Kerr, 1990;Kerr and Jirik, 1990;Combes, 1993;Hardage et al, 1994). Levey, Finley, and Sippel (1994) state that the period from 1950 through 1968 was the primary development phase of the Stratton field.…”

Reservoir architecture modeling: Nonstationary models for quantitative geological characterization. Final report, April 30, 1998

“…(c) A better mapping of the channels can be achieved using the procedure proposed by Hardage et al (1994) to get the original depositional surface. The seismic flattening technique is not available to us.…”

“…The VSP calibration is very important to identify the faulted horizons. We see from (Hardage et al, 1994) that the undeformed area is the upper Frio and a large part of the middle Frio formation. Few faults extend from lower Frio to middle Frio formation.…”