Real-Time Specific Energy Monitoring Reveals Drilling Inefficiency and Enhances the Understanding of When to Pull Worn PDC Bits

Real-Time Specific Energy Monitoring Reveals Drilling Inefficiency and Enhances the Understanding of When to Pull Worn PDC Bits Robert J. Waughman; Robert J. Waughman Woodside Energy Limited Search for other works by this author on: This Site Google Scholar John V. Kenner; John V. Kenner Hughes Christensen/Baker Hughes Search for other works by this author on: This Site Google Scholar Ross A. Moore Ross A. Moore Hughes Christensen/Baker Hughes Search for other works by this author on: This Site Google Scholar Paper presented at the IADC/SPE Drilling Conference, Dallas, Texas, February 2002. Paper Number: SPE-74520-MS https://doi.org/10.2118/74520-MS Published: February 26 2002 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Waughman, Robert J., Kenner, John V., and Ross A. Moore. "Real-Time Specific Energy Monitoring Reveals Drilling Inefficiency and Enhances the Understanding of When to Pull Worn PDC Bits." Paper presented at the IADC/SPE Drilling Conference, Dallas, Texas, February 2002. doi: https://doi.org/10.2118/74520-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE/IADC Drilling Conference and Exhibition Search Advanced Search AbstractOptimizing when to replace worn bits can yield substantial cost savings, especially in the high cost deep water offshore drilling fields, however, recognizing when a bit is "dull" and past its true economic life can be difficult. All too often, speculation and the hope that the bit will "break through" into something more drillable has remained the driving force for determining whether to change a bit or leave it in the hole. This decision making process is extremely inefficient and does not further the philosophy on continuous improvement.The concept developed to dramatically improve this inefficient decision process involved measuring the mechanical energy input at the drill rig floor; calculating the drilling specific energy; checking current formation type via real-time downhole gamma ray readings; comparing the specific energy with the benchmark new bit specific energy and then using these values to assess the bit's "dull" state. This method has been proven to work in synthetic based mud systems where balling does not mask bit dull condition. Since both balled-new bits and dull bits exhibit similar levels of inefficiency, it was imperative the operator proved this process worked in water-based drilling fluids that had replaced earlier synthetic muds. Synthetic muds were replaced by the water-based fluids due to environmental concerns, cost, and improved performance in WBM. Recently, the operator established that this process worked in water based mud systems that are treated with anti-balling chemicals. The case studies where this methodology was developed will be presented and discussed.IntroductionDrilling performance is commonly analyzed by comparing a given run to the average of the offsets. However, in offshore projects offsets are fewer and learning must be accelerated due to the inherent high cost. To reach a desired level of performance, aggressive targets must be set and plans to achieve those levels developed and implemented1. Utilizing real-time drilling efficiency and gamma ray data to monitor bit dull state is one approach refined and utilized by this operator in particularly troublesome areas.In order to estimate the bit dull state from drilling efficiency data the level of understanding of how incremental bit wear effects performance for different drilling conditions had to be improved. Galle2 and Bourgoyne3 developed early mathematical models for approximating the effects of bit wear on drilling performance (Figs. 1 and 2). Many performance models exist today but they typically fail to capture the dependencies on formation hardness and balling tendencies versus the type of drilling tool used (PDC, Tungsten Carbide Insert, or Mill Tooth) (Fig. 3). In a previous work we classified performance expectations across a range of tools and drilling conditions4 (Fig. 4) and will now use this information to interpret bit dull state. The following field examples illustrate when a bit should have been pulled and the consequences of not doing so on the performance of the subsequent bit runs and estimated cost impact. An overview of these three examples discusses how an improved level of understanding and monitoring technique enhances the understanding of when to pull worn PDC bits. Keywords: iadc spe 74520, real-time specific energy, bit selection, kenner, drilling operation, gamma ray, waughman, operator, decision process, new bit Subjects: Drill Bits, Drilling Operations, Bit design This content is only available via PDF. 2002. IADC/SPE Drilling Conference You can access this article if you purchase or spend a download.