Abstract

Exploitation of thin oil columns sandwiched between a gas cap and water leg poses a unique challenge for development of such reservoirs worldwide, especially for those with high permeability and strong aquifer support. Issues important for reservoir management involve locating the current fluid contacts and optimizing well placement, as coning effects from both gas and water could severely hinder recovery.

The paper presents a field case study demonstrating the use of horizontal wells to improve oil recovery for thin oil columns affected by gas-cap and active water support. The paper discusses reservoir management practices applied, varying from use of reservoir modeling for identifying current fluid contacts to selection of completion strategies for optimizing oil recovery. A practical and cost-effective methodology, from reservoir modeling to landing horizontal wells, is discussed. Specific guidelines to complete wells in thin oil columns with respect to gas-cap size, well placement, spacing, well length, and rate control are provided.

Field data from Serang Field in the Kutei Basin of East Kalimantan are discussed. These examples demonstrate thin oil columns under water drive can be effectively exploited with horizontal wells via integration of technology and a multi-disciplined team environment.