ABSTRACT: The Lake Arthur Complex, Jefferson Davis and Vermilion Parishes, Louisiana: How It Fits into the Regional Depositional Framework of the Camerina "A" to Miogypsinoides "A" Interval
Norman E. Smith
The Lake Arthur Complex is one of the many normal mega-sized structural features that fit into the normal South Louisiana regional framework when completely studied and understood. This Complex covers in excess of 100 mi2, being approximately two townships North-South and one and one-half townships East-West, located in Jefferson Davis and Vermilion Parishes, Louisiana. To explain this mega-feature requires an understanding of the regional structure and of the stratigraphic depositional patterns of each of the major paleontological sequences from the older Bolivina mexicana through the younger Discorbis (restricted) intervals, covering sediments of middle Oligocene age to the younger early Miocene age.
The Lake Arthur Complex encompasses six producing field areas as recognized by the Louisiana Department of Conservation. These fields produce from multiple sands ranging in age from middle Oligocene through early Miocene. The productive areas are related to a combination of their structural relationship to the overall complex, the stratigraphic depositional patterns of the producing sands as related to regional depositional faulting, and the stratigraphic depositional patterns of the producing sands related to the growth history of this Complex. Each of these variables, or a combination of these variables, has a significant controlling effect on the individual producing areas within the Complex.
One of the more significant producing intervals of the Lake Arthur Complex is the sand packages in the Camerina "A" to Miogypsinoides "A" middle Oligocene sediments. This interval produces on the north flank of the Complex in T-10-S, R-4-W; on the south flank in T-11-S, R-3-W; on the structural crest and in associated crestal fault block traps. Ultimately the Lake Arthur Complex may produce in excess of 5 tcf of gas with the Camerina "A" to Miogypsinoides "A" responsible for approximately 75% of the estimated production.
Each of the significant Camerina "A" to Miogypsinoides "A" producing areas in the overall complex is discussed structurally and stratigraphically, including the relationship to the overall regional depositional framework and history of the Camerina "A"-Miogypsinoides "A" stratigraphic interval.
The conclusions that have resulted from this study and analysis of the Lake Arthur Complex are that it does fit into a normal structural
and depositional framework for South Louisiana and does not require a localized special case explanation for any portion of the Complex.
AAPG Search and Discovery Article #90999©1990 GCAGS and Gulf Coast Section SEPM Meeting, Lafayette, Louisiana, October 17-19, 1990