Rock matrix and fracture analysis of flow in Western tight gas sands: 1986 annual report: Phase 2

Technical Report · Wed Apr 01 04:00:00 EST 1987

OSTI ID:6469695

Morrow, N R; Buckley, J S; Cather, S M; Brower, K R

The objective of this project is to develop reliable core analysis techniques for tight sands; these are essential to proper formation evaluation. Comparison of thin section porosity to pore volume has been used to develop a measure of quality of pore space. Natural fractures play a dominant role in production from tight sands. All available thin sections (about 600 in all) and MWX core on hand have been screened for the presence of natural fractures. Relative permeabilities to gas along healed (calcite-filled) fractures have been determined. Results show that the calcite filled fractures heal to where they have roughly the same permeability as the matrix, although some differences in the pressure sensitivity of the fracture and the matrix were observed. Permeabilities for fresh cores (not allowed to dry out) have been compared with results for conventional (dried) cores to determine what changes result from drying. Results obtained to date show that drying can affect the permeability and relative permeabilities of tight gas sands but the effect is not serious. UV microscopy is being employed to examine much finer features of pore structure (of the order of a few tenths microns) than is possible by conventional petrographic microscopy. Comparison of pore structure of a low permeability gas sand at ambient pressure with that at 5000 psi confining pressure supports a previous conclusion that sheet pores at grain boundaries tend to close up with increase in overburden pressure. 10 refs., 18 figs., 4 tabs.

• Research Organization: New Mexico Inst. of Mining and Technology, Socorro (USA). New Mexico Petroleum Recovery Research Center
• OSTI ID: 6469695
• Report Number(s): NMRDI-2-74-4324; ON: DE87900773
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
ADSORPTION
DATA
DESORPTION
DRILL CORES
DRYING
ELEMENTS
EXPERIMENTAL DATA
FAILURES
FLUIDS
FRACTURES
GASES
INFORMATION
MEDIUM TEMPERATURE
MICROSCOPY
NITROGEN
NONMETALS
NUMERICAL DATA
PERMEABILITY
POROSITY
PRESSURE EFFECTS
RESERVOIR ROCK
ROCKS
SANDSTONES
SATURATION
SEDIMENTARY ROCKS
SORPTION
SURFACE AREA
SURFACE PROPERTIES
VAPORS
WATER SATURATION
WATER VAPOR