Schlumberger

Case Study: Borehole Images Help Optimize Well Placement and Completion

Resistivity- and imaging-while-drilling service enables Wyoming operator to identify and characterize fractures along 3,000-ft lateral

Challenge:

  • Place long horizontal wellbore within 10-ft highly fractured layer of chalk bench.
  • Evaluate fractures along lateral section.

Solution: Use MicroScope high-resolution resistivity-while-drilling and imaging-while-drilling service for real-time structural interpretation and fracture identification.

Result:

  • Kept 3,000-ft lateral within 10-ft target of best quality pay.
  • Acquired high-resolution images to facilitate fracture identification and fault estimation and provide structural analysis.
  • Optimized stage designs for hydraulic fracturing.

Keep wellbore within target zone

An operator in Wyoming, USA, planned to develop the Niobrara formation in the Denver-Julesburg basin by combining horizontal drilling with multistage hydraulic fracturing. This formation consists of up to four laterally continuous chalk benches with intervening marls. Both permeability and porosity in the Niobrara chalk are relatively low, and production was expected to be enhanced by natural fractures. From historical drilling data in the area, it was known that the 33-ft “C” bench layer was the most attractive interval. This was reconfirmed and refined by openhole logs run in a pilot hole, where the operator identified a 10-ft window as the final lateral zone target. Keeping the wellbore within the highly fractured layer identified in the pilot hole would require accurate real-time information to guide steering decisions.

Make proactive well placement decisions

The operator achieved the well placement needed to optimize recovery by using MicroScope service to provide real-time acquisition and transmission of high-resolution electrical borehole images, azimuthal gamma ray measurements, and multi-depth measurement of formation resistivity. Analysis of this information in real time allowed proactive well placement decisions to be made by comparing the apparent dip of the formation to the borehole trajectory.

Maximize reservoir contact and optimize fracturing stages

Use of MicroScope service enabled the operator to maximize reservoir contact in the desired chalk bench. In addition, analysis of the high-resolution MicroScope images facilitated fracture identification, fault estimation, and structural analysis to optimize stage designs for hydraulic fracturing. The packers were staged to complete similar zones together and placed away from large open fractures. Sleeve ports were positioned close to open natural fracture swarms.


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