Reservoir characterization of the Upper and Lower Repetto reservoirs of the Santa Clara field-federal waters, offshore California

Abstract

This thesis presents the characterization of the Upper and Lower Repetto reservoirs of the Santa Clara field, which lies seven miles offshore of Ventura County, California. The approaches that we adopted for this reservoir characterization are based on the analysis of field production data. These reservoir characterization approaches include: The application of the Fetkovich/McCray decline type curve to estimate original oil-in-place, drainage area, flow capacity, and a skin factor for each well. This approach requires converting the field production data for each well to dimensionless decline flowrate, dimensionless rate integral, and dimensionless rate integral-derivative functions. These functions are then simultaneously plotted against dimensionless decline time so that a unique match of these plots can be obtained using the Fetkovich/McCray decline type curve (in this research, data conversion and type curve matching are performed using a software package). The analysis of plots of reciprocal production rate versus material balance time to estimate "movable" or recoverable oil reserves. This new material balance approach is used in conjunction with a semi-analytical method of graphical analysis (pressure drop normalized rate versus cumulative oil production), which also provides estimates of recoverable oil reserves. Together, these plotting techniques provide good estimates of the estimated ultimate recovery for each well. Our approaches for the analysis of field production data allow us to provide recovery factors for each well (using our estimates of original oil-in-place and estimated ultimate recovery). Furthermore, we were able to generate maps of original oil-in-place, estimated ultimate recovery, flow capacity, and permeability for both the Upper and Lower Repetto reservoirs.