Deployment of an ROP Predictor Tool for Real-Time Bit Optimization
Deployment of an ROP Predictor Tool for Real-Time Bit Optimization Since 1965, Specific Energy principles have been used to predict bit performance and analyze rate of penetration (ROP) and bit efficiency. Factors that create drilling inefficiency include bit dull, bit balling, bottom hole balling/cleaning issues, torque and drag and drillstring vibrations. These are often evident with high specific energy values. Based on these principles, Chevron has established proprietary relationships for bit-specific coefficient of sliding friction and mechanical efficiency as a function of the rock’s confined compressive strength (CCS). CVX then uses these relationships to predict reasonable and achievable ROPs with associated bit torque for several bit types, which are most commonly used in our global operations. The effect of Mud weight, blade count and cutter size to the coefficient of sliding friction and efficiency are considered in the ROP predictions. The relationships have proven to be of high value, a globally accurate drilling tool for improving overall bit performance and reducing well costs. Applied real-time, the tool identifies inefficient drilling conditions, provides operations personnel reliable information to make more informed decisions and achieve the best possible performance out of the bit that is in the hole, as well as, quantify the impact of parameter changes.
Despite concentrated development efforts spent in numerous optimization models and techniques, ultimately their value is either realized or lost in deployment. In an effort to achieve maximum value while rapidly deploying the ROP drilling tool, CVX identified three distinct service strategies dependent on the well complexity and the wellsite resources available. This presentation will describe the deployment process and present case histories of this successful tiered approach including the incremental benefits gained when bit performance prediction/selection modeling was coupled with real time downhole measurements. The limitations and increased data requirements necessary with complicated wellbore geometries will also be presented.
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