Gyro Guidance Techniques and Telemetry Methods Prove Economical in Onshore Multiwell Pad Drilling Operations in the Piceance Basin
Wellbore collisions and accurate well placement are major concerns in Chevron U.S.A. Inc.’s multi-well pad drilling operations in the Piceance Basin in Colorado. Up to 24 wells are drilled from a single pad with two rows of well slots. As a result of the high well slot density, gyroscopic survey systems must be run during kickoff operations in most wells due to magnetic interference.
Several methods of obtaining high accuracy rate gyroscopic (gyro) survey data have been employed, including:
- Rate Gyro single-shot surveys run on wireline;
- Gyro-While-Drilling (GWD) system incorporated in the Measurement-While-Drilling (MWD) string communicating with mud pulse telemetry; and
- GWD system incorporated in the MWD string communicating with electromagnetic (EM) telemetry.
This paper analyzes the performance of the three survey methods with respect to safety exposure, rig time, cost of service, equipment logistics, personnel requirements and operational performance. Field data is analyzed from more than 100 wells. This represents the largest database known by the authors for comparison of these service types presented in published literature.
Results indicate a solid justification for incorporating the gyro in the MWD string for the following reasons:
- Saves rig time by eliminating the separate wireline;
- Decreases safety risk exposure by eliminating wireline operations;
- Minimizes risk of stuck bottomhole assembly (BHA) due to static operations during wireline surveying;
- EM technology when combined with the gyro creates an accurate, efficient, and reliable surveying system when compared with mud pulse-conveyed telemetry;
- Improved drilling control resulted from being able to steer continuously while drilling with the gyro in the MWD string; and
- Accurate well placement has decreased well collision exposure with no wellbore collisions to date.
Incorporating rate gyro systems in the MWD string while drilling has proven economical in the more costly offshore environment for a number of years (Eaton 2005). Applying the technology successfully to less expensive onshore projects can increase efficiency and bring additional benefits in reduced logistical requirements and safer operations.
The Skinner Ridge Field encompasses approximately 100,000 acres and is located in the Piceance Basin of northwestern Colorado. The primary play in the Piceance Basin is the unconventional tight gas of the Mesaverde Formation, which ranges in depth from 6,000 to 6,500 ft true vertical depth (TVD) at the Skinner Ridge Field.
Exploratory drilling has occurred in Skinner Ridge off and on since the 1980s, with full field development beginning in the summer of 2007. The acreage covers the western edge of the Roan Plateau, where several valleys are found throughout the field