3-DIMENSIONAL SEQUENCE STRATIGRAPHY AND SUBTLE STRATIGRAPHIC TRAPS ASSOCIATED WITH SYSTEMS TRACTS - WEST CAMERON REGION, OFFSHORE LOUISIANA, GULF-OF-MEXICO

Three-dimensional sequence stratigraphy is a potent exploration and de velopment tool for the discovery of subtle stratigraphic traps. Reserv oir morphology, heterogeneity and subtle stratigraphic trapping mechan isms can be better understood through systematic horizontal identifica tion of sedimentary facies of systems tracts provided by three-dimensi onal attribute maps used as an important complement to the sequential analysis on the two-dimensional seismic lines and the well log data. O n new prospects as well as on already-producing fields, the additional input of sequential analysis on three-dimensional data enables the id entification, location and precise delimitation of new potentially pro ductive zones. The first part of this paper presents four typical hori zontal seismic facies assigned to the successive systems tracts of a t hird- or fourth-order sequence deposited in inner to outer neritic con ditions on a elastic shelf. The construction of this synthetic represe ntative sequence is based on the observed reproducibility of the horiz ontal seismic facies response to cyclic eustatic events on more than 3 5 sequences registered in the Gulf coast Plio-Pleistocene and Late Mio cene, offshore Louisiana in the West Cameron region of the Gulf of Mex ico. The second part shows how three-dimensional sequence stratigraphy can contribute in localizing and understanding sedimentary facies ass ociated with productive zones. A case study in the early Middle Miocen e Cibicides opima sands shows multiple stacked gas accumulations in th e top slope fan, prograding wedge and basal transgressive systems trac t of the third-order sequence between SB15.5 and SB 13.8 Ma.