ABSTRACT: Managing geologic uncertainty to optimise horizontal wellbore placement in real time

Weller, Geoff P¹, Benny Poedjono¹, and M. Shah Redza Haniff²
(1) Schlumberger, Kuala Lumpur, Malaysia
(2) Petronas Carigali Sdn Bhd, Kuala Lumpur, Malaysia

Horizontal and extended reach wells are often drilled in order to maximise reservoir penetration and hence productivity. However, at the same time they can also expose the operator to increased risk of missing his or her desired objectives in areas of relatively high geologic uncertainty.

The concept of actively controlling the placement of the wellbore during the drilling process, using formation evaluation derived from real-time log data (GeoSteering) is now no longer new. But recent developments in the modelling and drilling techniques used, and also in the quality and quantity of data available in real time while drilling, have allowed much more aggressive planning of horizontal and extended reach wells in areas of higher geologic uncertainty. These areas may previously have been considered uneconomic due to the risks involved.

Several wells drilled recently in South East Asia are used to illustrate the application of new and innovative techniques to successfully drill horizontal and multi-lateral wells despite the wells being targeted in areas of higher geologic uncertainty and requiring very tight tolerances to achieve the required objectives. Methods to control the wellbore placement despite the challenges presented by multiple fault blocks, thin oil columns, and time - depth conversion are discussed.

Advances in real-time formation evaluation and modelling, as well as directional drilling techniques are presented, together with their application in horizontal and extended reach wells.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia