A well plan is essentially a decision-making roadmap for choosing equipment required for drilling the required wellbore. The operator's ability to properly assess offset drilling data and key lithology factors to match available BHA tools and procedures plays a large role in determining project success. Accordingly, the software support systems utilized to interpret and extrapolate data have a direct impact on the ability of drilling engineers to optimize operations.

Historically, most well plans were assembled using data from offset wells and prior experience. However in most cases, a rudimentary analysis could not produce a comprehensive picture of the complex, interdisciplinary downhole dynamics that affect drilling performance, especially in the case of limited or missing offset data. Even when reliable data was available, a one-dimensional analysis has failed to completely exploit the available informational value from offset wells. This has forced engineers to be more conservative when designing wells and include more contingencies. The result is operators are drilling in a reactive manner, which often led to decisions resulting in performance degradation rather than optimization.

To solve the problem and improve drilling performance in areas of limited/inaccurate offset data, engineers have developed a Mechanical Efficiency Ratio optimization system (MER) that accurately measures the BHA's use of available energy. The modeling tool was tested in several applications and accurately predicted performance including ROP, footage capabilities and dull bit condition. The tool used data and evaluation of rig capabilities, bit/BHA performance, downhole behavior and formation challenges including high-rock strength and interbedded lithologies.

The authors will present three case studies that outline how the software program was used to measure system efficiency to determine which bit would have the highest ROP, total footage capabilities and best dull grade estimate compared to offset runs. The MER will also determine if the system (bit/BHA) or the optimized drilling parameters will improve drilling efficiency.

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