Strategies for Optimized Oil Recovery in Fluvial-Dominated

Deltaic Reservoirs in the Lower Woodbine Group, East Texas Field

William A. Ambrose, Tucker F. Hentz, Florence Bonnaffé,

Robert G. Loucks, and Fred P. Wang

Bureau of Economic Geology, The University of Texas at Austin,

University Station, Box X, Austin, Texas  78713-8924

ABSTRACT

Although East Texas Field has produced 5.42 billion stock-tank barrels since its discovery in 1930 and has a high recovery efficiency of 77%, the field still has great potential for additional oil production owing to poor sweep efficiency and variability in reservoir properties of discontinuous sandstones in lower Woodbine fluvial-dominated deltaic reservoirs.  Strategies for producing additional oil in these reservoirs include deepening existing wells and redesigning waterfloods to provide optimal pressure support by targeting relatively thicker (>15-ft [>4.5-m]) distributary-channel sandstones that pinch out into muddy interdistributary-bay and delta-plain deposits over short distances (commonly <500 ft [>152 m]).  Early production in the field focused on thick (typically >50-ft [>4.5 m]), conglomeratic sandstones in an upper interval composed of lowstand, incised-valley-fill deposits, with few wells penetrating underlying highstand deltaic sandstones.  Additional oil has recently been produced from deepened wells in the north part of the field, where these wells encounter distributary-channel and proximal-delta-front sandstones that were isolated from previous production.  Waterflooding could locally be made more cost effective by reducing the number of water-injection wells in sandstone-poor areas where production has declined to as little as two barrels of oil per day.  Other options include designing limited waterfloods to provide pressure support in areas where discontinuous distributary-channel-fill and crevasse-splay sandstones have not been penetrated by existing wells or where distributary-channel sandstones are favorably oriented along the structural gradient.  Successful implementation of these strategies will depend on a thorough understanding of the reservoir sandstone architecture and its control on fluid flow. 

Ambrose, W. A., T. F. Hentz, F. Bonnaffé, R. G. Loucks, and F. P. Wang, 2009, Strategies for optimized oil recovery in fluvial-dominated deltaic reservoirs in the lower Woodbine Group, East Texas Field:  Gulf Coast Association of Geological Societies Transactions, v. 59, p. 35-47.

AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana