Minimizing Lost Circulation Non-Productive Time for Naturally Fractured Formations

Lost circulation is a unique challenge unlike other factors contributing to non-productive time (NPT). Due to the variability in the nature and type of lost circulation prone formations; there is no universal solution to this challenge. This publication presents a novel approach to guide the decision-making process of which and when to apply a certain treatment as compared to another. If implemented correctly, a significant reduction in NPT related to lost circulation can be expected. Also, the cost of each treatment, as well as the NPT that is associated with the treatment, were examined in this study. Data from over 2000 wells were gathered from various sources and reports; the treatments were classified by scenario –partial, severe, and complete losses –as well as cost, efficiency, and formation type. This paper is developed based on probabilities, expected monetary value (EMV), and decision tree analysis (DTA) to recommend the best-lost circulation strategy for each type of losses. This is the first study that considers a detailed probability and cost to treat the lost circulation problem. Thousands of treatment scenarios for each type of losses were conducted, and the EMVs for all scenario are calculated. For each type of losses, the lowest EMV treatment strategy that is practically applicable in the field and makes sense –was selected to be used to treat each type of losses to minimize NPT and cost. If the losses didn't stop after utilizing the proposed treatment strategies, it is recommended to use liner hanger to isolate the losses zone and then continue drilling.