Case Studies: Fault Identification Using Borehole Image Log for Mississippian Limestone Horizontal Well Completion Design

Yinghao Chen, Bruce Miller, Charles Wickstrom, and Shane Matson

Our case studies show that an effective well completion design is the key to the success of the Mississippian Limestone horizontal well oil production. In another words, understanding the natural fracture system, especially fault/cave attributes, and choosing the right places for stimulation are very important to maximize oil and minimize water production. Many features on the borehole wall are observed and can be quantified with borehole image log, including fault or cave and natural fracture systems, beside other geological features. All these features demonstrate different aspects of the reservoir properties. We routinely review and understand these image log features, along with other information, before we complete a well. A perfect zone for cluster perforation and hydraulic fracture treatment has 3 key attributes – good porosity, a multi-strike natural fracture system and a distance from a large fault/cave – all can be identified with the borehole image log. The first 2 are the foundation for maximizing production rate. The third element is vital for reducing water cut in the Mississippian limestone reservoir. The major point of this presentation is a large fault/cave could connect the oil reservoir to aquifers above or below, which may increase the water cut significantly. A few case studies will be talked. Multi-strike natural fracture systems and large faults/caves were interpreted with borehole image logs. These interpretations were used for the well completion designs. Higher oil and lower water rates had been recorded after the wells were completed. 

AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013