A client in South Oman was struggling to place additional wells to maintain the production levels in a Semi Steam Assisted Gravity Drainage (SAGD) project due to very high collision risks. Real Time High-Definition Surveys (HDS) application was used in conjunction with In-Field Referencing (IFR) to reduce the size of Ellipse of Uncertainties (EOU) and increasing the Separation Factor (SF) while drilling.
In a SAGD project, the placement of well either Horizontal Producer (HP) or Horizontal Injector (HI) is very critical and any deviation can cost dearly in terms of production rate. A post run survey enhancement will most likely is not going to produce the desired results and can lead to costly plug well situation. A special real time survey enhancement procedure with the help of an exclusive application was used to increase the survey density. This application provided high density industry standard MWD surveys, by using advanced algorithms with continuous azimuth & inclination data from MWD tool.
This combination benefited the client in multiple ways and most significantly, additional 70 horizontal producer & injector wells are drilled in last 4 years, which otherwise were not possible to drill. These additional wells resulted in over five million barrels of produced oil per year for the client, which translates into 204 million USD annual revenue. Additionally, it helped achieve the objective of placing the well at optimum spot to minimize the water break through and reduce the produce water. Also, the reduction in tortuosity by removing additional turns for collision avoidance resulted in longer well life and better production rates. In addition to that, managed to plan another 50 well trajectories with the help of this new technique to be drilled in near future. The well drilled with this approach has up to 30% smaller EOU size and will help the project in future with more room to place additional wells.
This survey enhancement application can benefit similar projects worldwide in a variety of ways. On one hand this will help operators to optimize the production by drilling additional wells in very congested areas, and on the other hand this will also help the Sub-Surface Team (SST) to calibrate their existing geological model with more accurate reservoir boundaries.
