Schlumberger

Case Study: Geomechanics Assessment of Stability Eliminates Second Casing String to Save USD 200,000

TuffTRAC tractor conveyance of triple-combo, spectroscopy, and acoustic logging tools obtains critical data for Wolfcamp lateral

Challenge: Construct a petrophysical and geomechnical model that determines horizontal wellbore stability while reducing drilling costs.

Solution: Use the TuffTRAC cased hole services tractor to convey a triple-combo toolstring, ECS elemental capture spectroscopy sonde, and Sonic Scanner acoustic scanning platform to collect the petrophysical and geomechanical data necessary for constructing a mechanical earth model (MEM).

Result: Used the MEM incorporating the high-resolution 3D geomechanical measurements by the Sonic Scanner platform to identify intervals with potential hole instability that enabled the EXL Petroleum to mitigate drilling risk by employing an appropriate mud weight, repositioning the casing shoe point, and installing a short liner string instead of running an intermediate casing, saving approximately USD 200,000.

A need for geomechanical insight

EXL Petroleum wanted to better understand wellbore stability and determine the best mud weight to optimize drilling of its next horizontal well in the Wolfcamp Formation in the Delaware basin. Schlumberger petrotechnical experts proposed constructing a MEM using geomechanical and petrophysical data from two previous wells.

Critical data acquisition on TuffTRAC tractor

Measurements made by the Sonic Scanner acoustic scanning platform supply high-resolution compressional, fast and slow shear, and Stoneley wave slownesses. The resulting 3D dataset supports both basic geomechanical interpretation of homogeneous isotropic material and sophisticated geomechanical interpretation of inhomogeneous anisotropic materials.

To convey the Sonic Scanner platform along with a triple-combo Platform Express integrated wireline logging tool and ECS sonde to measure complementary petrophysical data in the deviated wells, the TuffTRAC cased hole services tractor was used. The TuffTRAC tractor is the shortest and most efficient tractor in the industry, with active traction control and reverse tractoring capability for superior maneuverability in complex deviated and horizontal cased wells.

Wellbore stability analysis to optimize drilling the horizontal

The full 3D acoustic characterization performed with the Sonic Scanner acoustic scanning platform addressed both intrinsic and drilling-induced anisotropy. With this comprehensive mechanical understanding of the drilling environment, the MEM accurately suggested casing shoe points, appropriate mud weights, and drilling practices to maximize wellbore stability. Because potential instability was flagged for the interval from 10,293 to 10,298 ft at 56° deviation in the Wolfcamp Formation, EXL Petroleum was able to mitigate risk by hanging a short liner string across the interval before finishing drilling. A 51⁄2-in casing was then run to total depth to successfully avoid having to run an intermediate 7-in string, resulting in a savings of USD 200,000.


Download: Geomechanics Assessment of Stability Eliminates Second Casing String to Save USD 200,000 (5.18 MB PDF)

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Data Flagged Potential Instability for the Interval

TuffTRAC cased hole services tractor to convey a triple-combo toolstring, ECS elemental capture spectroscopy sonde, and Sonic Scanner acoustic scanning platform to collect the petrophysical and geomechanical dataTuffTRAC cased hole services tractor to convey a triple-combo toolstring, ECS elemental capture spectroscopy sonde, and Sonic Scanner acoustic scanning platform to collect the petrophysical and geomechanical data
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