Recognizing high-porosity/low-permeability sandstone reservoirs with routine logs: Case history
Conference
·
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
OSTI ID:6891805
- Abilene Christian Univ., TX (USA)
For Mid-Continent-type sandstones, good porosity (15-20%) does not always signify good permeability (tens to hundreds of millidarcys). Characterization of the potential producibility of many reservoirs is based primarily on wireline logs because cores are seldom available. Unfortunately, log responses indicating low permeability can be subtle and easily overlooked. Failure to recognize low-permeability intervals results in errors in log interpretation, which cause (1) overestimation of net effective pay, (2) overly optimistic reserve calculations, and (3) errors in exploitation strategy. A case study of Pennsylvanian deltaic sandstones in Concho County, Texas, shows the reservoir sandstones to have good porosity, but also to have numerous thin shaly zones of low permeability. Integration of log and core data reveals and/or confirms subtle indications of low permeability intervals on the open-hole logs (dual induction, gamma ray, sp, density, and neutron). Permeability/porosity crossplots show that the quality of the reservoirs is determined by the depositional environment of the sand. Integration of the log and core data necessitated a significant revision of the reservoir model. In some wells, 80-95% of the productive capacity is contained in 40-60% of the net pay. Vertical permeability barriers were discovered in the reservoir-quality sand (K{sub vertical} of 1.5-2 md vs. K{sub horizontal} of 74-196 md). Careful analysis of open-hole logs, especially when some core data is available from offset wells, can identify low-permeability intervals and greatly improve reservoir characterization.
- OSTI ID:
- 6891805
- Report Number(s):
- CONF-9003145--
- Conference Information:
- Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:2
- Country of Publication:
- United States
- Language:
- English
Similar Records
[open quotes]2-Step[close quotes] log analysis of the Spellacy reservoir in the giant Midway-Sunset Field, Kern County, California
{open_quotes}2-Step{close_quotes} log analysis of the Spellacy reservoir in the giant Midway-Sunset Field, Kern County, California
Crossplot technique for the analysis of the carbon/oxygen log
Conference
·
Sun Dec 31 23:00:00 EST 1995
· AAPG Bulletin
·
OSTI ID:6592912
{open_quotes}2-Step{close_quotes} log analysis of the Spellacy reservoir in the giant Midway-Sunset Field, Kern County, California
Conference
·
Mon Dec 30 23:00:00 EST 1996
·
OSTI ID:425887
Crossplot technique for the analysis of the carbon/oxygen log
Conference
·
Thu Dec 31 23:00:00 EST 1981
· SPE Repr. Ser.; (United States)
·
OSTI ID:6325419