Structural and Stratigraphic Study of the N-Sand in the Helis East Black Bay Field

Zobell, Elizabeth¹, Anish Kumar², Brian Briscoe³, Jonathan W. Malone³, James P. Stoyanoff⁴, Paul N. Lawless⁵, George R. Kear³ (1) Brigham Young University, Provo, UT (2) Schlumberger, Houston, TX (3) Schlumberger, New Orleans, LA (4) Helis Oil & Gas Company, L.L.C, New Orleans, LA (5) Helis Oil, New Orleans, LA

A structural and stratigraphic study the Helis East Black Bay Field (offshore Louisiana) was undertaken to determine the geological history of the N-Sand. The study used water based mud microresistivity image, dip data, and a 3-D seismic data volume across the project area. Values of structural dip obtained from high quality microresistivity images were similar to those determined from seismic two-way travel time values for the N-Sand.

The paper describes the methodology used in the study. Structural dip values were determined from the shales using dips from microresistivity images. Paleocurrent flow direction, and energy of deposition was determined by integrating water based mud microresistivity images and structurally deleted dips (stratigraphic dips). The complete interpretation was accomplished using static and dynamic borehole images in conjunction with the stratigraphic dips to determine the depositional history.

Deposition was quite active and variable within the section of interest: Middle to upper-Middle Miocene, the section containing a number of transgressive and regressive cycles. Additionally, observations are correlated to published sequence stratigraphy of the Middle Miocene.

The paper concludes with recommendations from image and dip interpretations of paleocurrents combined with seismic amplitudes.