In the PEMEX Southern Drilling and Producing Region, which includes all land wells drilled in the southeastern states of Mexico, directional drilling has gradually increased to 75% of wells drilled. Producing zones in the region are also deep with difficult targets under high pressure and temperature. These factors have led PEMEX to seek out new technology in an effort to optimize drilling and producing operations.

One of the special projects defined for the year 2001 was to evaluate the application of running a high-accuracy gyroscopic directional survey instrument in tandem with PEMEX logging systems. In the process, the Southern Region engineering group and the PEMEX wireline logging division worked with a local survey company to build a special housing to run the gyro probe on top of several different logging instruments.

This paper describes the development of the tandem gyro-logging combination tool and tests in three wells. System performance is analyzed and comparisons are made between gyro survey results and other survey instrumentation. Conclusions indicate that the success of running two services in one run in the well saves substantial rigtime and eliminates the costs of additional wireline runs. Furthermore, the application of high-accuracy survey information may prove valuable in more accurate wellbore placement and reservoir mapping—leading to enhanced production. In the future, the combination run may also have value in detecting the orientation of imaging logs in both cased and open hole to determine fracture orientation and formation dip angle.

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