Fracture characterization and diagenesis in the Clipper field, Sole Pit basin, southern north sea

Conference · Wed Sep 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6914731

Franssen, R C.M.W.; Brint, J F ^[1]; Sleeswijk Visser, T J ^[2]; Beecham, A ^[3]

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1. KSEPL/Shell Research, Rijswijk (Netherlands)
2. Shell Expro Lowestoft, Suffolk (United Kingdom)
3. Shell Expro, London (United Kingdom)

The Clipper field in the Sole Pit basin produces from tight Leman sandstones of the Rotliegende Group (Lower Permian). The reservoir consists of aeolian sediments. Gas production comes from open natural fractures and dune slipface sands with highly variable rates. The effects of fractures and diagenesis on reservoir quality were investigated. Three fracture networks have been observed in two highly deviated cored wells. Fault-related fractures occur close to, and parallel with, seismically mapped faults. Fold-related fractures occur as two sets of conjugate fractures, with the local maximum compressive stresses ([sigma][sub 1]) trending northeast-southwest and northwest-southeast, respectively. The dominant fracture types are cataclastic and dilational shear fractures. The cataclastic shear fractures were reopened and both fracture types are partially filled by silica, carbonate, and anhydrite cements. The main cement types within the sandstone matrix include dolomite, silica, anhydrite, illite, and ferroan carbonates. Early carbonate cements precipitated during initial burial from a mixture of Rotliegende groundwater and marine pore-fluids from the higher temperatures from Zechstein-derived pore fluids. Pore-filling and fracture-related ferroan carbonate and silica cement precipitated between temperatures of 100-150[degrees]C from isotopically evolved pore fluid. Integration of these data with the burial history and regional geological data reveal that the fault-related fractures formed during the formation of the Sole Pit rift basin in the Middle to Late Jurassic. The fold-related fractures formed during the Late Cretaceous inversion. The open fractures that contribute to production are associated with the inversion-related deformation. Modeling of these fracture networks, calibrated against available well data, can be used to define areas with high shear fracture density and assist development of fields in the Sole Pit basin.

• OSTI ID: 6914731
• Report Number(s): CONF-9310237-; CODEN: AABUD2
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:9; Conference: American Association of Petroleum Geologists (AAPG) mid-continent section meeting, Amarillo, TX (United States), 10-12 Oct 1993; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
RESERVOIR ROCK
GEOLOGIC FRACTURES
SANDSTONES
CONCRETIONS
SEDIMENTS
DIAGENESIS
CEMENTS
GEOLOGIC FAULTS
GEOLOGIC HISTORY
GEOLOGIC MODELS
JURASSIC PERIOD
NATURAL GAS
NORTH SEA
SEDIMENTARY BASINS
SHEAR
ATLANTIC OCEAN
BUILDING MATERIALS
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MATERIALS
MESOZOIC ERA
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
030200* - Natural Gas- Reserves
Geology
& Exploration