Over the recent years, new MEMS gyro tools have demonstrated sufficient accuracy and robustness for wellbore positioning2,3. That means gyro surveying becomes more and more affordable and widespreaded. But MWD surveying is still a foundation of the wellbore positioning. And next logical step would be fusion of these two measurements for the best accuracy. Two decades ago, a study was done to combine MWD and gyro measurement for significant accuracy improvement1. However, that method has not been implemented due to its several drawbacks.
Currently, we could significantly improve the method from the paper1. The elaborated algorithm calculates the well path with the best achievable accuracy based on the MWD-GWD fusion. That is ensured by the precise survey corrections, realistic error modeling, and internal quality control. The fusion algorithm has been integrated into the automatic survey processing workflow. Also, we implemented a survey program proposal algorithm for the fusion result to utilize the result in standard drilling anti-collision software.
1. Chia, C.R., Phillips, W.J., and Aklestad, D.L. A New Wellbore Position Calculation Method. SPE 85111, 2003
2. Ledroz, A., Bang, J., and Weston, J. New Instrument Performance Models for Combined Wellbore Surveys: A Move Toward Optimal Use of Survey Information. SPE 178826, 2016
3. Lowdon, R., Igarashi, J., and Sargin, D. Solid State Gyro While Drilling Technology Provides Accuracy and Robustness. SPE 187220, 2017