Uncertainty and Risk Management: Waterflood Pilot Design and Surveillance Proposal for a Giant Multi-Layered Sandstone Reservoir

Wei, Chenji (Research Institute of Petroleum Exploration & Development, PetroChina) | Li, Yong (Research Institute of Petroleum Exploration & Development, PetroChina) | Song, Benbiao (Research Institute of Petroleum Exploration & Development, PetroChina) | Tian, Changbing (Research Institute of Petroleum Exploration & Development, PetroChina) | Li, Baozhu (Research Institute of Petroleum Exploration & Development, PetroChina) | Zhou, Jiasheng (Research Institute of Petroleum Exploration & Development, PetroChina) | Zheng, Jie (Research Institute of Petroleum Exploration & Development, PetroChina) | Luo, Hong (Research Institute of Petroleum Exploration & Development, PetroChina) | Lan, Jun (Research Institute of Petroleum Exploration & Development, PetroChina)

OnePetro 

Abstract

Accurately understanding the geological and dynamic characteristics determines the recovery and life cycle of a reservoir. Several uncertainties and risks exist during the development especially for giant multi-layered sandstone reservoirs. Pilot is one of the most effective steps to manage risks and reduce uncertainty, which help better understand the reservoir, expose the conflict during development, propose corresponding surveillance plan, determine development plan, and eventually improve the reservoir performance.

This study focuses on a giant Cretaceous multi-layered sandstone reservoir in the Middle East, which started to produce since 1960s without any energy supply, and the current reservoir pressure is approaching the bubble point pressure. Therefore, water flooding is urgently needed. In order to reduce uncertainty and risks, criteria and workflow of selecting waterflood pilot is proposed by integrating the geology, dynamic data, well status, and existing facilities etc.. 4 pilots are selected and each pilot represents a typical reservoir type to better understand the performance and adaptability of different development plan. Each pilot has its own specific objectives and detailed operation plan. Finally, surveillance plans are proposed based on geological understanding, dynamic behavior, and simulation results.

According to the proposed criteria and workflow, pilots are selected to represent good, medium, and poor reservoir quality respectively. Pilot I is selected as an example to be discussed in detail. The reasons to select this pilot, well pattern and spacing, and perforation strategy discussion are presented. Finally, surveillance is divided into different groups, and implementation plan of different types of surveillance is determined.

This study offers a comprehensive case study that supports the engineers and geologists for better understanding the reservoir and optimizing waterflooding plan for this reservoir. Moreover, it offers an integrated methodology of pilot selection and surveillance proposal for other similar oilfields.