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Book Chapter

Flexible Well-path Planning for Horizontal and Extended-reach Wells

By
E. J. Stockhausen
E. J. Stockhausen
ChevronTexaco Exploration and Production Technology Company, Houston, Texas, U.S.A.
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G. E. Smith
G. E. Smith
ChevronTexaco Exploration and Production Technology Company, Houston, Texas, U.S.A.
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J. A. Peters
J. A. Peters
ChevronTexaco Exploration and Production Technology Company, Houston, Texas, U.S.A.
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E. T. Bornemann
E. T. Bornemann
Schlumberger Oilfield Services Houston, Texas, U.S.A.
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Published:
January 01, 2003

Abstract

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.

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Contents

AAPG Methods in Exploration Series

Horizontal Wells: Focus on the Reservoir

Timothy R. Carr
Timothy R. Carr
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Erik P. Mason
Erik P. Mason
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Charles T. Feazel
Charles T. Feazel
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American Association of Petroleum Geologists
Volume
14
ISBN electronic:
9781629810553
Publication date:
January 01, 2003

GeoRef

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