SOUTH RAVENSPURN GAS FIELD, OFFSHORE UNITED KINGDOM: SEQUENCE STRATIGRAPHY AND HETEROGENEITY MODELLING IN A LOW PERMEABILITY CONTINENTAL RESERVOIR
Published:December 01, 1997
M. L. SWEET, 1997. "SOUTH RAVENSPURN GAS FIELD, OFFSHORE UNITED KINGDOM: SEQUENCE STRATIGRAPHY AND HETEROGENEITY MODELLING IN A LOW PERMEABILITY CONTINENTAL RESERVOIR", Shallow Marine and Nonmarine Reservoirs: Sequence Stratigraphy, Reservoir Architecture and Production Characteristics, Keith W. Shanley, Bob F. Perkins
Download citation file:
South Ravenspurn Field, located in UKCS blocks 42/30 and 43/26, is a large (> 1 TCF gas initially in place) dry gas field that is currently producing from 22 vertical, hydraulically fractured wells. The reservoir is the Lower Leman Sandstone of the Permian Rotliegend Group. As the field is at the edge of the Lower Leman Sandstone play fairway, reservoir quality is poor.
In 1996 to assess the potential for drilling infill wells the South Ravenspurn geologic and reservoir engineering models were completely rebuilt. By recognizing eolian sequence boundaries, lacustrine transgressive surfaces and maximum flooding surfaces a high-resolution stratigraphic framework was established for the field using core and wireline data. This framework was critical to understanding the continuity of eolian facies flow units and the effects on vertical transmissibility of lacustrine highstand shales. Based on this framework and outcrop analogs a 3-D geologic model of the reservoir was constructed using geostatistical techniques. This model had strongly deterministic elements to honor the facies trends seen regionally and the occurrence of facies changes at major stratigraphic boundaries. Rock properties were assigned to each facies based on core, wireline and well test data.
The resulting geologic model was upscaled to a full-field simulation model. During the history matching process data on gas production and reservoir pressure were used to improve the fine-scale geologic description. The resulting full-field model predicted lateral depletion of the higher permeability eolian units and poor vertical drainage of the reservoir.