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An Investigation of a Salt-Dome Environment at South Timbalier 54, Gulf of Mexico

by Little, Jr

Abstract (Summary)
Salt domes have been studied in the Gulf Coast region to look at how, why, and where saline waters are located within these field areas. Fluid flow model and pathway studies can be helpful to the research of saline water migration because it can be correlated to hydrocarbon migration in petroleum exploration. The South Timbalier 54 field occurs over a salt dome that sits at approximately 3,048 meters beneath the seafloor. Two major faults were found originating from the salt dome up into the shallow section of the field. The sands were deposited in fluvial, deltaic, or marine environments. The original salinity of these sediments would be between 0 to 35 g/L if the fluids in the pore space were the original fluids. Salinity logs were calculated for forty wells surrounding the salt dome to locate any presence of salinities outside of 0 to 35 g/L. The Revil et al. method (1998) was used to estimate salinity from the data of the gamma ray, density, and resistivity log. Saline waters were found to be located in this field and the values could be group into four salinity zones. Each zone represents a change in the value of salinity from the shallowest to the deepest log. The first zone contains values of 20 to 30 g/L, the second contains values from 60 to 130 g/L, the third contains values from 30 to 45 g/l, and the fourth zone contains values from 60 to 110 g/L. Mud weight data from a well near the salt dome shows that the top of overpressure is between 3,657 meters and 3,962 meters. The fluids are forced out of overpressure up the side of the salt dome. These fluids dissolved the salt to create the high salinities and then were forced into the major faults. Through these faults the saline waters were expelled into the adjacent sediments creating the high salinity zones of the field by using the faults as a migration pathway. The low values of zones one and three represent infiltration of brackish waters and a possible low permeability zone respectively.
Bibliographical Information:

Advisor:Juan Lorenzo; Jeffrey Hanor; Jeffrey Nunn

School:Louisiana State University in Shreveport

School Location:USA - Louisiana

Source Type:Master's Thesis

Keywords:geology geophysics

ISBN:

Date of Publication:07/11/2003

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