Abstract
A mature oil field reservoir is characterized by gathering the geological and petrophysical data with the dynamic data. The product allows the defining of vertical reservoir units and their continuity along the field. Reservoir properties, seals and barriers are determined by pressure data and compared with the petrophysical interpretation.
This document presents a profound study on pressure data interpretation and how to integrate this information with a petrophysical-geological model obtained by well log data analysis. The sands correlation, reservoir properties, faults location and vertical seals, are interpreted at first with the well log data (GR-SP-RES-DN-PE) and seismic data. Then the pressure data points are analyzed taking into account the previous interpretation to confirm the sands vertical connectivity, fluid gradients and the fluid contacts. Additionally, the mini PBU transients are diagnosed by means of computer-aided type curves to evaluate flow regimes in the near wellbore region and to calculate the permeability. Finally, a fully integrated static petrophysical model is built based on the previous study.
The geological cross section is compared before and after the pressure data integration. Ten recently drilled wells from three different reservoir areas with pressure data available are analyzed and presented in this paper. The pressure data evaluation allows identifying the 4 different formation units and its water oil contact (WOC), according to the pressure gradients. The pressure behavior along the horizontal section permits to estimate the sands continuity and the connectivity between three areas. The static reservoir pressure analysis serves to validate and improve the basic well log interpretation and should be a part of the formation evaluation workflow. In addition, a near wellbore model is a strong tool to support and improve the type curve diagnose and interpretation of dynamic data.
This paper provides a great insight on reservoir characterization and the benefits of the pressure logging tool for gathering static and dynamic information into geological models. In many cases formation testing data interpretation is based solely on the spherical flow analytical model. This straightforward approach might bias some features of the near wellbore region, which can only be assessed by pressure transient diagnosis (e.g. pressure derivative). Modeling of formation pressure testing as an interpretation tool strongly improves the near wellbore region dynamic description.
