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Geo-Steering Horizontal Wells: Case Studies Demonstrate the Value of Fuzzy Logic Directional Steering Guidance

Mark, Sandra1 and Michael S. Stoner2
1Black Hills Exploration & Production, Golden, CO
2Stoner Enginnering LLC, Golden, CO

     The success of horizontal drilling in Cretaceous reservoirs is initiating many new development programs throughout the Rocky Mountain basins. The productive zones are often thin, and the ultimate performance of a well is usually dependant upon the number of feet through which the lateral wellbore travels through the zone.
     Geo-steering a horizontal well in real-time is geological interpretation at its most stressful. The objective of geo-steering interpretation is to describe the stratigraphic location of the wellbore as drilling progresses. This task is complex because the known 3- dimensional curving wellbore must be resolved with the unknown 3- dimensional curving and often faulted reservoir. Modern geo-steering requires depth-accurate formation evaluation measurements acquired with Logging While Drilling (LWD) tools. The most common such tool measurement in the Rocky Mountains is gamma ray. Modern geo-steering involves correlating LWD signal data with a type log to discern the stratigraphic location of the wellbore.
     Software that performs the mathematics necessary for geosteering has been available for many years, but there are new techniques that take the interpretation to a new level. Technical Hole Deviation (THD) is the mathematical unification of planned versus actual directional well paths. THD quantifies how a directional well path differs from its planned trajectory, and provides much greater detail than is supplied by the directional company. When THD data are combined with the geo-steering interpretation through Fuzzy Logic processing, genuine steering guidance is provided. The benefits of this additional insight have been recognized in several recent wells.

 

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah