Measuring Microinvisible Loss MILT Time in Drilling Operations

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Abstract
Within both productive and nonproductive time (NPT), a drilling operation can include invisible lost time (ILT), which is the time lost because a portion of the drilling operations is not performed at maximum efficiency. Within this ILT, another dimension of lost time can exist because of the inherent nature of the process, use of unoptimized equipment, or because the process might not have been performed at the optimum efficiency. Both NPT and ILT concepts have been discussed in the literature. Some concepts are based on the maximum theoretical performance (MTP), and others are based on threshold time calculation. Regardless of the estimation method used, NPT and ILT are generally quantified in the literature as products of downhole conditions. Another dimension of NPT: microinvisible lost time (MILT) is introduced in this work. MILT is identified as being affected by two major factors: surface equipment design and efficiency and process optimization. MILT also includes ergonomic human inefficiencies attributable to these factors. A case study is presented to identify the MILT using an online statistical analysis method. It can be integrated with future management and well design plans to improve the efficiency of drilling operations. The objective is to help identify the commonly ignored hidden factors that contribute to NPT; consequently, it can help promote faster, more efficient, and more cost-effective drilling.