Gas-cap effects in pressure-transient response of naturally fractured reservoirs
- Sultan Qabous Univ. (Oman)
- Univ. of Southern California, Los Angeles, CA (United States)
During the primary production life of an oil reservoir, segregation of oil and gas within the fissures before reaching the producing wells could create a secondary gas cap if no original gas cap were present, or will join the expanding original gas-cap gas. This paper presents a theoretical framework of gas-cap effects in naturally fractured reservoirs. General pressure solutions are derived for both pseudosteady-state and unsteady-state matrix-fracture interporosity flow. Deviation from the fracture or fracture-matrix response occurs as the gas-cap effect is felt. Anomalous slope changes during the transition period depend entirely on the contrast between the fracture anisotropy parameter, {lambda}{sub l}, and matrix-fracture interporosity parameter, {lambda}, and between the total gas-cap storage capacitance (1 {minus} {omega}{sub 1}) and oil-zone matrix storage (1 {minus} {omega}). A composite double-porosity response is observed for {omega}{sub 1} {le} {omega}{sub 1c} and 1.0 {le} {lambda}{sub 1}/{lambda} {le} 1,000. A triple-porosity response is observed for {omega}{sub 1} {ge} {omega}{sub k} and 140 < {omega}{lambda}{sub 1}/{lambda} < 1.0E05.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 452257
- Journal Information:
- SPE Formation Evaluation, Vol. 12, Issue 1; Other Information: DN: Paper presented at the 1990 SPE Annual Technical Conference and Exhibition, New Orleans, LA (US), September 23--26, 1990; PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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