Application of pressure/fluid sampling measurement for the understanding of the complex fluid movement and communication in a mature, carbonate, heterogeneous reservoir

Abstract

The lower cretaceous Formation reservoirs in Offshore Abu Dhabi represent a regressive cycles of sedimentation developed with shoal, laggonal, subtidal and supratidal sediments. This formation includes various types of lithologies along the reservoir column: Anhydrite alternating with Dolomites, limestone.In such mature, heterogeneous oil reservoirs with a large gas cap, information may improve cost effective productivity, reduce the risks and improve the oil recovery. Special analysis of pressure measurement, fluid scanning and sampling while drilling is important to challenge open hole log saturation, to understand the behavior of each layer in the reservoir, to assess the communication between the sub layers, and to enhance the development schemes. This study is a synthesis of all the Open-hole Vertical Pressure Profiling data sush as formation evaluation and sampling that has been performed through the history of the fields.Investigations have been conducted on the identification of the in-situ reservoir fluid nature; the hydraulic vertical communication between layers; pressure maintenance mechanisms effect and pressure evolution through time and its link with lateral communication.Furthermore from operational point of view best practices have been developed for a safe and efficient procedure in terms of data acquisition and analysis with the limitations of the formation testing tool.