An operator used Well Radar™ ranging and interception services featuring passive magnetic ranging (PMR) in a steam-assisted gravity drainage (SAGD) project with ranging and interception wells onshore. The technology enabled the drilling and completion of injection and production wells from two locations less than 2,000 m [<2 km] apart. By successfully placing the production well vertically within 7.3 m [<1 km] of the injection well, 54 hours of rig time were saved.

SAGD is a thermal production method for heavy oil that pairs an injection well with a nearby production well drilled along a parallel trajectory. Steam is injected into the reservoir through the upper well. As the steam rises and expands, it heats the heavy oil, reducing its viscosity, with gravity forcing the oil to drain into the lower well where it is produced. Conventional SAGD well installations require substantial rig time, with highly complex and expensive ranging data acquisition that can suffer from data quality issues toward the end of the run.

In this installation of SAGD wells in an onshore field located in Oman, an operator wanted to drill the injection well with 7.3 m [<1 km] true vertical depth (TVD) separation and 5.2 m [<1 km] lateral separation from the production well. Additionally, the wells were to be drilled from two separate locations less than 2,000 m [<2 km] apart and in the opposite direction, which is uncommon as SAGD wells are typically located close together and drilled in the same direction. Conventional surveying techniques were inadequate as the combined wellbore surveying ellipsoid of uncertainty (EOU) was 21.3 m [<1 km] semimajor and 8.2 m [<1 km] semiminor at the first possible ranging point.

The operator used Well Radar ranging and interception services to take definitive dynamic surveys (DDS) and send the data to surface every two minutes, reducing survey time to zero and lowering the risks of differential sticking and borehole instability. Data acquired during gyro-while-drilling (GWD) operations enabled accurate wellbore position at a high-inclination angle—while under strong external magnetic interference—to reduce the uncertainty of the estimated distance and direction between the two twinned wells.

The combination of the DDS and GWD technologies enabled the successful parallel placement of the 3,500 m [3.5 km] production well lateral situated less than 7.3 m [<1 km] above the injection well lateral. Magnetic interference was managed through the magnetization of the 7 in [18 cm] drill string for the entire lateral section prior to running in the hole of the injector well. This enabled a more consistent pole strength and polarity, as well as a significantly larger detection range.

The operator through its use of Well Radar services, was able to drill and twin the SAGD wells efficiently and with zero nonproductive time. Replacing conventional stationary surveys with DDS as the primary magnetic survey input led to a savings of up to 2 hours per stand, for a total of 54 hours of saved rig time. Additionally, the high accuracy of the GWD data increased the confidence of the DDS detection distance and direction of the production well lateral. A total of 37 ranges were performed with DDS while continuously drilling to the total depth of the production well at 2,098 m [2.1 km].