Diagenetic History and Its Effect on Reservoir Quality and Reservoir Characterization of Sandstone Sequences of Matulla Formation, October Field, Gulf of Suez, Egypt

Abstract

The study of diagenesis in petroleum industry are very important and critical point for reservoir evaluation where diagenesis parameters enhance or reduce reservoir porosity and permeability which are the main factors that control the productivity of hydrocarbon from carbonate or sandstone reservoirs. In Matulla formation of October field, the sandstone represent the only reservoir where carbonates have no opportunity to produce hydrocarbon in because of charge problem and also the reservoir character represent very low porosity and permeability. Porosity can be restored and enhanced at depth. The study revealed that the Matulla Formation is composed of wave and tide influenced mixed siliciclastic carbonate rocks interbedded with some oolitic ironstone beds. Primary facies and diagenetic modification both play key roles in the reservoir potential of the Matulla Formation. This study revealed that the major porosity exist in the sandstone is secondary porosity interpreted from the detailed texture petrographic study with building diagenetic historical model with depth. The distribution of this secondary porosity along the field in association with the sandstone facies maps give an overview for the accumulation of these secondary porosities which related to diagenetic events that took place with time and depth. This sandstone / diagenesis maps used as a key in the development plan of Matulla sandstone sequence in October field which provided to the reservoir engineering team to point them out for the places to get optimum recovery from the stimulation jobs. The petrology study of the rock textures also solved many problems that faced the development team during the enhanced oil recovery project where highlighted of how preventing the formation damage that may occur by using incompatible fluid/ rock solutions. The main conclusion of this study that the reservoir quality of sandstone sequence of Matulla Formation not depend on the primary intergranular porosity as was believed in the old studies but the main contributor to the hydrocarbon is the secondary porosity which show great influence on the permeability, fluid flow and rock typing distribution along the field and revealed the solution of many problems for petrophysical parameters distribution in reservoir property modeling and also led to reevaluation for the facies models that build in the days before.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018