Exploring for hydrocarbons offshore Mexico, Pemex planned to drill an exploratory well targeting a high-pressure, high-temperature (HPHT) reservoir in the shallow waters of the Sureste Basin. To reach their reservoir objective, Pemex engineers developed a well plan that required a complex J-shaped profile with a curve that inclined to 25° in the 8.5in hole section.

To achieve this profile, Pemex required a rotary steerable system (RSS) with precise inclination control to drill the curve. Challenging the well plan further, this system also needed the ability to operate in heavy weight mud and in a high-temperature (HT) environment – 338°F above the 8.5in section and expected to exceed 356°F, which is above the 350°F rating of most HT-rated RSSs.

In addition to having the ability to control the direction of the drill bit, the driller needs to know where the well is being drilled and in what direction. Traditionally, this is done by running a wireline with logging tools to survey the well, which would determine where the well has been drilled and orientation of the well. Each survey then would require pipe to be tripped multiple times and for sections of the well to be drilled in order for the survey to see if the well is on target or if corrections need to be made, all while rig time accumulates.

However, with the precise inclination control needed to follow the complex well profile, real-time directional data delivery was required. As a result, Pemex equipped the bottomhole assembly (BHA) with Schlumberger’s arcVISION array resistivity compensated service and TeleScope service. The arcVISION service provided the driller with gamma ray, inclination and annular pressure-while-drilling data, and TeleScope provided high-speed telemetry-while-drilling. With these two services, the real-time directional data, needed for the driller to follow the complex will profile, was provided.