Subsurface Structure and Stratigraphy of Kent Bayou-Turtle Bayou-North Turtle Bayou Complex, Terrebonne Parish, Louisiana

ABSTRACT The Kent Bayou-Turtle Bayou-North Turtle Bayou Complex is in northwestern Terrebonne Parish, Louisiana, along a prolific Miocene producing trend. Drilling was initiated in the area in 1936, but the first hydrocarbon reservoir tapped was found by the discovery well at the Turtle Bayou field in 1957. Active exploration is still in progress in Turtle Bayou. The hydrocarbon producing zones lie within a biostratigraphic unit characterized by Bigenerina nodosaria directa, Bigenerina humblei, and Amphistegina “B” faunal zones. The oldest sediments encountered are characterized by Robulus “43”. The basic structural configuration of the Kent Bayou-Turtle Bayou area is that of two anticlinal features with a northeast-southwest-trending axis of elongation. North dip off these two structures is cut by a series of down-to-the-basin faults. Hydrocarbons trapped by closure on the upthrown sides of these faults are produced in the North Turtle Bayou field. Pronounced changes in the character of the sediments from outer shelf to deep-water type deposits, and thickening in the section below the Bigenerina humblei marker across this series of faults, indicate that the area was near the edge of the continental shelf during lower Miocene time. This area is also marked by the apparent updip limit of sediments characterized by the deep-water “Harang-like” faunal assemblage. The intrusion of a salt mass probably began during lower Miocene time.