ABSTRACT: Reservoir geochemistry: study of reservoir continuity in two pay sands of Gandhar field, Cambay basin, India

Reservoir geochemistry is developing into an important tool for evaluation of reservoir continuity and compartmentalisation, which is one of the important parameters for improved reservoir management. This study on GS-11 and GS-12 sands of Gandhar field is based on gas chromatographic fingerprinting of naphthenic and aromatic compounds present in oils. Oils of single reservoirs show very close similarity which has been assessed through star diagrams and cluster analysis of peak ratios. Detailed geochemical investigation suggests that source rock depositional environment of GS-11 and GS-12 oils are similar.

In GS-11 sand, lateral reservoir continuity exists between wells GB, GC, GD and GA. This is also the case in GJ, GI and GE. These two groups of oils are closer to each other in relation to GL and GK. The distinction among the oil group is probably due to the presence of fluid barriers. The compositional variation in the oils of GF, GH and GG suggest that these are most probably present in three different reservoir compartments. Detailed gaschromatographic investigation of residual oils indicates that fluid communication exists in sand GS-11 between wells GX and GZA. In GS-12 sand, fluid communication exists between wells GN, GO and GP. These oils show compositional variation from other studied oils GT, GU, GV, GX, GY, GZ and GZA which are correlatable among themselves and seem to be produced from single reservoir compartment.

No fluid communication was found between the two sands in the studied part of the Gandhar field.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia