RAINS, DAVID B., Texas A&M University, Dept. of Geology, College Station, TX

ABSTRACT: Characterization, Origins, and Petroleum Potential of High-Amplitude Reflection Packets, HARPs, on the Middle and Lower Mississippi Fan

High amplitude reflection packets, HARPs, refer to sheetlike sand deposits with high-amplitude seismic-reflection character that are formed in many submarine fan systems. Based on observations from the Amazon Fan, HARPs are thought to be related to channel avulsion events. When levees fail, sediment gravity flows move through the break and into interchannel lows, where lack of confinement results in sheet-like sand deposits. HARPs and associated channel-levee complexes have been identified on the middle and lower Mississippi submarine fan. The purposes of this investigation are to identify and map for HARPs, characterize the HARPs in terms of their seismic attributes, create a depositional model for HARPs, and evaluate the hydrocarbon potential of HARPs on the middle and lower Mississippian Fan. An extensive data set, including 2D and 3D seismic surveys and borehole data, will be used for this study. Specifically, the study will encompass several Pliocene depositional lobes of the Mississippi Fan, and a distinctive near-surface seismic unit (a possible HARP), which can be mapped over the Mississippi Canyon area. Post-dating this possible HARP are four large submarine paleocanyons: Old and Young Timbalier, SW Pass, and Ursa canyons of upper Pliocene age. This study will attempt to map the depositional source of the HARP(s) and the maximum downdip extent of the post-HARP channels. A depositional model for these units will be developed after detailed mapping and seismic facies interpretations are complete. This study will have important implications for exploration and production in other deep-water submarine fan systems.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid