Utilizing High Fidelity Surveys to Optimize Placement of U-Turn Wells

The drilling of U-turn wells to replace two separate lateral wells has been increasing over the last few years. The first one being drilled in 2019, and 112 more being drilled since May of 2020. The objective of this paper is to show the vast improvement in positional uncertainty that is gained when using High-Fidelity surveys vs Advanced MSA corrected surveys or no corrections at all. 17 wells will be in this study with a combination of real time surveys that were either High-Fidelity, or Advanced MSA. The High-Fidelity surveys will be used to reduce positional uncertainty and reveal TVD error that is caused by minimum curvature. There are many benefits to drilling a U-turn well. It is effectively drilling two laterals in one and can cut drilling time almost in half when comparing one or two U-turn wells with a two or four well pad. These added benefits put more pressure on the drilling team to succeed. The curve needs to be landed appropriately to set up the first leg. The first leg cannot veer off in either direction for the sake of spacing of the second leg. The turn cannot be too sharp, or too wide to set up the second leg. Then the second leg must keep proper distance from the first leg to optimize production. Utilizing high fidelity surveys will increase the knowledge of the position of the wellbore both in terms of azimuth and inclination, or TVD. For all the wells in the study, the reduction of the calculated ellipse of uncertainty from MWD to corrected with and without High-Fidelity was compared to show how much improvement is gained when using High-Fidelity surveys. After processing it was observed that the average reduction of the horizontal EOU from MSA + Sag to High-Fidelity surveys was 8.43%. With the average vertical EOU reduction being 26.9%. The largest reduction horizontally was 17.61%, and 31% vertically. The smallest reduction horizontally was 2.02% and vertically 21.46%. In all 17 wells the High-Fidelity survey listing reduced the ellipse of uncertainty with the greatest impact coming in terms of TVD uncertainty. The TVD placement is also greatly improved with High-Fidelity surveys. Revealing up to 9′ of TVD error at landing point, and up to 25′ of TVD error at TD. The reduction of uncertainty obtained while using High-Fidelity surveys is greatly beneficial while drilling a well and provides useful information to the team drilling the U-turn well. Improving the certainty of the position both horizontally, and vertically plays a significant role in properly drilling the well and maximizing production. At the same time, reducing the risk of any anti-collision or lease line crossing.