Water Flooding in Compartmentalization Sand Stone Reservoir : Case Study of P field in Block 7E- Sudan

Abstract

This research focuses on several important issues of reservoir characterization and data integration for water flooding in compartmentalization sand stone reservoir. The goal of reservoir characterization is to estimate the spatial distribution of the reservoir properties, e.g., permeability and porosity, by proper integration of all types of data available (either static or dynamic), putting into consideration the integration of production history data, Geophysical & Geological data, and well test data in this work. The main objective of this research is to assess / evaluate the feasibility of water flooding in compartmentalizing sandstone reservoir to provide pressure support and sweep oil out of the pore space to improve oil production. And to validate this assumption of reservoir characterization was put in consideration to improve the accuracy in defining the dynamic relationships between all factors (rock properties, fluid properties, and reservoir data). In order to achieve best water flooding practices. In determining the suitability of a given reservoir for water flooding, these factors are considered: reservoir geometry, lithology, Reservoir depth, porosity, permeability (magnitude and degree of variation), continuity of reservoir rock properties, magnitude and distribution of fluid saturations, fluid properties, relative permeability relationships, and primary reservoir driving mechanisms. Reservoir characterization procedure considering all above mentioned factors have been applied to one pool of P field in Block 7E– Sudan (Compartmentalized sandstone reservoir) which supports and confirms the findings of this research. Actual reservoir Characterization applied on water flooding program to determine ultimate recovery and improve timing of production events, such as initial water breakthrough and peak production. P field is composed of P fault block and F fault block generally with an anticline background. The stratigraphic section is comprised of sandstones and clay stones. The target is Yabus and Samaa formation of lower Paleocene. Yabus and Samaa formations are sub-divided into 9 zones. Oil reservoirs are of edge water or bottom water in P field. Multi-pays are distributed in the field. Generally the oil pools in Yabus and Samaa I are stratified with edge water, Samaa II and Samaa III are massive with bottom water. Interpretation methodology was develop and applied to pilot water injection for F Fault Block reservoir; several parameters were included, mainly related to the geological model, dynamic model and operational conditions. A general methodology used in simulation work is organized in several steps based on three levels. To achieve optimum water injection design for P field (F Fault Block) various simulation sensitivity runs were conducted based on four key points: injection rate, timing of water injection, injector bottom hole pressure, and injection zone connection. The most important conclusion of this work is that the results of the simulation sensitivity runs demonstrate that water injection is more favorable depletion method in terms of the stability period of oil production and cumulative oil recovery. Analysis has shown that pressure drawdown is only slight due to the support of edge water in Yabus VI reservoir, and water cut will increase quickly after water injection, therefore declining oil rate mostly suspected, and it is demonstrated that the feasibility of compartmentalizing sandstone reservoir for water flooding while intensive reservoir characterization process is considered.