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Title: Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas

Abstract

An approach that integrates detailed geologic, engineering, and petrophysical analyses combined with improved well-log analytical techniques can be used by independent oil and gas companies of successful infield exploration in mature Gulf Coast fields that larger companies may consider uneconomic. In a secondary gas recovery project conducted by the Bureau of Economic Geology and funded by the Gas Research Institute and the U.S. Department of Energy, a potential incremental natural gas resource of 7.7 bcf, of which 4.0 bcf may be technically recoverable, was identified in a 490-ac lease in Agua Dulce field. Five wells in this lease had previously produced 13.7 bcf from Frio reservoirs at depths of 4600-6200 ft. The pay zones occur in heterogeneous fluvial sandstones offset by faults associated with the Vicksburg fault zone. The compartments may each contain up to 1.0 bcf of gas resources with estimates based on previous completions and the recent infield drilling experience of Pintas Creek Oil Company. Uncontacted gas resources occur in thin (typically less than 10 ft) bypassed zones that can be identified through a computed log evaluation that integrates open-hole logs, wireline pressure tests, fluid samples, and cores. At Agua Dulce field, such analysis identified at 4-ft bypassedmore » zone uphole from previously produced reservoirs. This reservoir contained original reservoir pressure and flowed at rates exceeding 1 mmcf/d. The expected ultimate recovery is 0.4 bcf. Methodologies developed in the evaluation of Agua Dulce field can be successfully applied to other mature gas fields in the south Texas Gulf Coast. For example, Stratton and McFaddin are two fields in which the secondary gas recovery project has demonstrated the existence of thin, potentially bypassed zones that can yield significant incremental gas resources, extending the economic life of these fields.« less

Authors:
;  [1];  [2];  [3];  [4];  [5];  [6]
  1. (Univ. of Texas, Austin, TX (United States))
  2. (ResTech, Inc., Houston, TX (United States))
  3. (Research and Engineering Consultants, Inc., Englewood, CA (United States))
  4. (Envirocorp Services and Technology, Houston, TX (United States))
  5. (Pintas Creek Oil Company, Corpus Christi, TX (United States))
  6. (Coastal Texas Oil and Gas, Houston, TX (United States))
Publication Date:
OSTI Identifier:
6963154
Report Number(s):
CONF-9310237--
Journal ID: ISSN 0149-1423; CODEN: AABUD2
Resource Type:
Conference
Resource Relation:
Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States); Journal Volume: 77:9; Conference: American Association of Petroleum Geologists (AAPG) mid-continent section meeting, Amarillo, TX (United States), 10-12 Oct 1993
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; ABANDONED WELLS; EVALUATION; NATURAL GAS; ENHANCED RECOVERY; NATURAL GAS DEPOSITS; RESOURCE POTENTIAL; TEXAS; EXPLORATION; GEOLOGIC FAULTS; NATURAL GAS FIELDS; RESERVOIR ROCK; US DOE; DEVELOPED COUNTRIES; ENERGY SOURCES; FLUIDS; FOSSIL FUELS; FUEL GAS; FUELS; GAS FUELS; GASES; GEOLOGIC DEPOSITS; GEOLOGIC FRACTURES; GEOLOGIC STRUCTURES; MINERAL RESOURCES; NATIONAL ORGANIZATIONS; NORTH AMERICA; RESOURCES; US ORGANIZATIONS; USA; WELLS 030300* -- Natural Gas-- Drilling, Production, & Processing

Citation Formats

Ambrose, W.A., Levey, R.A., Vidal, J.M., Sippel, M.A., Ballard, J.R., Coover, D.M. Jr., and Bloxsom, W.E. Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas. United States: N. p., 1993. Web.
Ambrose, W.A., Levey, R.A., Vidal, J.M., Sippel, M.A., Ballard, J.R., Coover, D.M. Jr., & Bloxsom, W.E. Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas. United States.
Ambrose, W.A., Levey, R.A., Vidal, J.M., Sippel, M.A., Ballard, J.R., Coover, D.M. Jr., and Bloxsom, W.E. 1993. "Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas". United States. doi:.
@article{osti_6963154,
title = {Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas},
author = {Ambrose, W.A. and Levey, R.A. and Vidal, J.M. and Sippel, M.A. and Ballard, J.R. and Coover, D.M. Jr. and Bloxsom, W.E.},
abstractNote = {An approach that integrates detailed geologic, engineering, and petrophysical analyses combined with improved well-log analytical techniques can be used by independent oil and gas companies of successful infield exploration in mature Gulf Coast fields that larger companies may consider uneconomic. In a secondary gas recovery project conducted by the Bureau of Economic Geology and funded by the Gas Research Institute and the U.S. Department of Energy, a potential incremental natural gas resource of 7.7 bcf, of which 4.0 bcf may be technically recoverable, was identified in a 490-ac lease in Agua Dulce field. Five wells in this lease had previously produced 13.7 bcf from Frio reservoirs at depths of 4600-6200 ft. The pay zones occur in heterogeneous fluvial sandstones offset by faults associated with the Vicksburg fault zone. The compartments may each contain up to 1.0 bcf of gas resources with estimates based on previous completions and the recent infield drilling experience of Pintas Creek Oil Company. Uncontacted gas resources occur in thin (typically less than 10 ft) bypassed zones that can be identified through a computed log evaluation that integrates open-hole logs, wireline pressure tests, fluid samples, and cores. At Agua Dulce field, such analysis identified at 4-ft bypassed zone uphole from previously produced reservoirs. This reservoir contained original reservoir pressure and flowed at rates exceeding 1 mmcf/d. The expected ultimate recovery is 0.4 bcf. Methodologies developed in the evaluation of Agua Dulce field can be successfully applied to other mature gas fields in the south Texas Gulf Coast. For example, Stratton and McFaddin are two fields in which the secondary gas recovery project has demonstrated the existence of thin, potentially bypassed zones that can yield significant incremental gas resources, extending the economic life of these fields.},
doi = {},
journal = {AAPG Bulletin (American Association of Petroleum Geologists); (United States)},
number = ,
volume = 77:9,
place = {United States},
year = 1993,
month = 9
}

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  • Fluvial-deltaic sandstones represent a large percentage of reservoirs in U.S. fields that face premature abandonment, despite having an estimated 30 billion barrels of unrecovered oil. These heterogeneous sandstones possess excellent potential for incremental recovery of significant oil volumes currently isolated in untapped and incompletely drained reservoir compartments. Results from geological and petrophysical characterization of selected Frio reservoirs are being used both to identify specific infill and recompletion opportunities and to guide incremental recovery strategies in mature reservoirs throughout South Texas that are now on the verge of being abandoned. Reservoir mapping and stratigraphic facies analysis in Rincon field were usedmore » to describe depositional styles present within a 150-ft. sequence that has produced more than eight separate flow units in the Frio D-E reservoir interval record aggradational channel-fill sedimentation within an overall backstepping pattern, followed by development of stirk-oriented shoreface bars, and a return to channel deposition in an overall progradational regime. Differences in sandstone architecture between retrogradational and progradational units result in different degrees of reservoir compartmentalization that directly impact recovery efficiency. Petrophysical modeling based on evaluation of abundant core data and saturation estimates from special core analyses is being used to describe permeability structure, map remaining oil distribution, and target undeveloped reservoir compartments with large oil volumes. Better understanding of controls on the stratigraphic distribution of oil and its subsequent production in these sandstones has wide application to many other analogous reservoirs and is a key to optimizing incremental recovery in mature Frio reservoirs.« less
  • The Frio Fluvial-Deltaic Sandstone along the Vicksburg Fault Zone play of South Texas has produced nearly 1 billion barrels (Bbbl) of oil from fluvial-deltaic sandstones since field development began in the 1940`s. More than half the reservoirs in this depositionally complex play have been abandoned, even though large volumes of oil remain. Current efforts integrating geological and engineering reservoir characterization are being used to identify the location of unrecovered mobile oil, estimated at more than 1 Bbbl, that remains in unproduced reservoir zones in fields within this very mature play. Geologic and engineering data from Rincon field are being evaluatedmore » to identify interwell stratigraphic heterogeneity and potential for compartmentalization of significant volumes of unrecovered oil. The producing Frio reservoir interval, representative of other fields within the play, consists of a 1,000-ft-thick mixed aggradational and progradational sequence of fluvial channel-fill and delta-plain distributary-channel sandstones interbedded with low-permeability overbank, floodplain, and interdistributary mudstones. Oil reservoirs consist of multiple thin (0-40 ft) dip-elongate sandstone units that stack to form gross thicknesses of 50 to 100 ft. They occur both as narrow channel fills isolated vertically and laterally by low-permeability overbank and floodplain facies and as large channel complexes with multiple laterally coalescing sandstone lobes. These large channel-sandstone complexes provide ideal conditions for the isolation of oil accumulations in multiple reservoir compartments, many of which are now incompletely drained or completely untapped. Reservoir architectural mapping and facies studies are being used in conjunction with petrophysical data to identify heterogeneity style and degree of channel connectedness in each type of reservoir and to identify zones with high potential for recovering additional reserves.« less
  • Fluvial-deltaic sandstone reservoirs in the United States are being abandoned at high rates, yet they still contain more than 34 billion barrels of unrecovered oil. The mature Oligocene-age fluvial-deltaic reservoirs of the Frio Formation along the Vicksburg Fault Zone in South Texas are typical of this class in that, after more than three decades of production, they still contain 61 percent of the original mobile oil in place, or 1.6 billion barrels. This resource represents a tremendous target for advanced reservoir characterization studies that integrate geological and engineering analysis to locate untapped and incompletely drained reservoir compartments isolated by stratigraphicmore » heterogeneities. The D and E reservoir intervals of Rincon field, Starr County, South Texas, were selected for detailed study to demonstrate the ability of advanced characterization techniques to identify reservoir compartmentalization and locate specific infield reserve-growth opportunities. Reservoir architecture, determined through high-frequency genetic stratigraphy and facies analysis, was integrated with production history and facies-based petrophysical analysis of individual flow units to identify recompletion and geologically targeted infill drilling opportunities. Estimates of original oil in place versus cumulative production in D and E reservoirs suggest that potential reserve growth exceeds 4.5 million barrels. Comparison of reservoir architecture and the distribution of completions in each flow unit indicates a large number of reserve-growth opportunities. Potential reserves can be assigned to each opportunity by constructing an Sooh map of remaining mobile oil, which is the difference between original oil in place and the volumes drained by past completions.« less
  • The Frio Fluvial-Deltaic Sandstone Play of South Texas is one example of a mature play where reservoirs are being abandoned at high rates, potentially leaving behind significant unrecovered resources in untapped and incompletely drained reservoirs. Nearly 1 billion barrels of oil have been produced from Frio reservoirs since the 1940`s, yet more than 1.6 BSTB of unrecovered mobile oil is estimated to remain in the play. Frio reservoirs of the South Texas Gulf Coast are being studied to better characterize interwell stratigraphic heterogeneity in fluvial-deltaic depositional systems and determine controls on locations and volumes of unrecovered oil. Engineering data frommore » fields throughout the play trend were evaluated to characterize variability exhibited by these heterogeneous reservoirs and were used as the basis for resource calculations to demonstrate a large additional oil potential remaining within the play. Study areas within two separate fields have been selected in which to apply advanced reservoir characterization techniques. Stratigraphic log correlations, reservoir mapping, core analyses, and evaluation of production data from each field study area have been used to characterize reservoir variability present within a single field. Differences in sandstone depositional styles and production behavior were assessed to identify zones with significant stratigraphic heterogeneity and a high potential for containing unproduced oil. Detailed studies of selected reservoir zones within these two fields are currently in progress.« less
  • The Frio Fluvial-Deltaic Sandstone oil play of South Texas has produced nearly 1 billion barrels of oil, yet it still contains about 1.6 billion barrels of unrecovered mobile oil and nearly the same amount of residual oil resources. Interwell-scale geologic facise models of Frio Fluvial-deltaic reservoirs are being combined with engineering assessments and geophysical evaluations in order to determine the controls that these characteristics exert on the location and volume or unrecovered mobile and residual oil. Progress in the third year centered on technology transfer. An overview of project tasks is presented.