USE OF HEAVY MINERAL SUITES IN RESERVOIR SAND STUDIES IN THE HARRIET FIELD, BARROW SUB-BASIN, WESTERN AUSTRALIA

Abstract

Analysis of the heavy mineral suites in the reservoir at Harriet Field has significantly improved reservoir unit definition and correlation and provided information on facies changes and diagenetic history. It has provided further evidence for a stratigraphic barrier as a cause of the variation of the oil-water contact in the field.

The reservoir consists of a number of discrete sandstone bodies which are arranged in a multistorey manner.

The reservoir is further subdivided into compartments by minor faulting. Prior to the use of heavy mineral analysis, correlation between wells was often unclear. Such correlation is beyond the resolution of reflection seismology and the massive nature of the sandstones means that definition and correlation is uncertain when made on the basis of lithology combined with wireline logs. The time interval involved in the deposition of the reservoir sequence is too short to permit discrimination by palaeontological analysis.

Eight distinct sandstone bodies can be defined on the basis of analysis of the heavy mineral suites in the 14 wells of the field. The total composition of the suites, certain 'marker minerals' and various statistical indices have been used to define these sandstone units which are interpreted to be individual lobes within a submarine fan complex. The methods and results are illustrated with examples from the field. The results of the analysis show that heavy mineral populations can provide critical information for accurate reservoir mapping and analysis.