Flexible Well-path Planning for Horizontal and Extended-reach Wells
E. J. Stockhausen, G. E. Smith, J. A. Peters, E. T. Bornemann, 2003. "Flexible Well-path Planning for Horizontal and Extended-reach Wells", Horizontal Wells: Focus on the Reservoir, Timothy R. Carr, Erik P. Mason, Charles T. Feazel
Download citation file:
The value and success of horizontal and extended-reach wells depend on overall well-path design and the effective wellbore placement in the reservoir. Significant incremental value can be obtained by increasing the precision of well placements within or across stratigraphic lobes and by positioning the wells relative to fluid contacts. Four main factors that significantly impact the success of these types of wells are (1) geologic uncertainty, (2) borehole-position uncertainty, (3) unanticipated buildup rates and doglegs, and (4) communication and understanding between the geologist and the directional driller.
Previous articles on geosteering have discussed uncertainty factors that impact a drilling project and have recommended the development of contingency plans. This paper reviews the impact these factors have on the success of horizontal-drilling projects and describes a methodical approach to well planning and drilling that includes specific contingency-plan recommendations. This approach integrates local geologic information with a flexible well-path design.
The flexible well-path design method anticipates making path adjustments while drilling in order to improve the precision of well placement. The steps of this method include:
defining the project’s uncertainties
evaluating the need for drilling a pilot hole and for running specialized steering tools
designing a site-specific, flexible well-path plan using adjustable tangents to address uncertainties while drilling
designing a “key marker-bed tangent” to locate one or more key marker beds above the target objective, using real-time geologic and directional data
designing a “soft-landing tangent” to land the well at the desired well orientation in the target objective
applying advanced steering techniques in the lateral section of a horizontal well to maintain the desired position and orientation in the target objective
Use of this well-planning approach gives the well-construction team flexibility to react to real-time geologic and directional complexities without causing alarm. By understanding the complexities of the project and deploying these techniques, operators can realize a 20% or more increase in net present value (NPV) in their horizontal and extended-reach drilling projects.
Figures & Tables
Horizontal Wells: Focus on the Reservoir
This book provides an overview of the new technical approaches required for best use of horizontal and extended-reach technology in different reservoir situations. The volume is a selection from more than 50 papers presented at an AAPG/SPWLA Hedberg Research Symposium, “International Horizontal and Extended Reach Well Symposium: Focus on the Reservoir,” held in The Woodlands, Texas, on October 10 14, 1999. The 16 chapters describe horizontal and extended-reach wells and drilling programs in a variety of geologic settings all over the world.