Print this pageComparison and Results of a Borehole Gravity Survey with Core and Log Data through an Allochthonous Salt Sheet in Ship Shoal South Additions, Offshore Louisiana
DESANTIS, J. E. and H. L. HARRISON
A BHGM (Borehole Gravity Meter) survey was conducted in the Phillips No. 1 Ship Shoal 337 well, located offshore Louisiana in the Gulf of Mexico. Gravity readings were made at fifteen stations within the borehole through a 6,214 foot thick salt glacier and ten readings were made at stations in the borehole below the salt.
BHGM densities are compared to density from rotary sidewall cores and FDC density log. The BHGM data determines the average density of the salt body and core and log data are discrete samples of the salt body. Significant differences exist between the three data sets and a comparison will be presented.
The borehole is located near a steep salt flank and borehole gravity could show a structural effect due to the proximity of the meter to a significant salt edge. This effect alters the borehole gravity readings which yields a less than real salt density. The magnitude of the effect could give insight to the accuracy of the salt flank location relative to the wellbore as imaged from 3-D seismic data. Accurate salt densities are also important in gravity modeling for determining salt thickness and subsalt sedimentary section thickness. Implications for selecting the proper salt density for gravity modeling will be discussed.