Underbalanced Operations

Abstract

Formation damage to some extent occurs in all wells. As a result the objective of drilling, completion and workover designers is to reduce the effects of damage to economically acceptable levels. The underbalanced operation is one such technology to exploit the formation to its full potential. At present many of the onshore reservoirs of India are in depleted conditions with good amount of recoverable reserves. Various issues involved in the underbalanced operations have been investigated. Laboratory screening procedures for evaluating the effectiveness of underbalanced operation for a specific application has been elaborated. Benefits and limitations of underbalanced operations are identified. Appropriate candidate selection for underbalanced operations is elaborated. Fluid operations used in underbalanced techniques are also discussed. The project provides a detailed study in how to plan for underbalanced operations to achieve success in drilling, completion and workover to the oil field. The study emphasizes advantages of this technology, formation stability, well control, environmental restrictions, minimize / avoid formation damage with employing non-damaging fluid and the development of water based low gravity workover fluid formulations for sub-hydrostatic reservoir field. It is very difficult to maintain the underbalanced condition during horizontal well operations due to poor hole cleaning. In that case formation damage occurs when underbalanced condition is lost, for such condition laboratory experiments and evaluation of non-damaging fluid at bottom hole environment is performed which will provide guaranteed economic incentives. The technology implementation would minimize formation damage, reduce requirement of subsequent stimulation/activation jobs, and would result in higher productivity gain. Objective of the project is to improve the productivity from sub-hydrostatic Indian reservoirs.