Drilling Optimization of Argentina Horizontal Tight Sand Wells

Abstract

Abstract Argentina tight sand wells present a hostile drilling environment with hard, abrasive, and interbedded lithology. Consequently, bottomhole assembly (BHA) behavior is difficult to predict; tools and drilling performance are often affected, leading to poor rates of penetration (ROP), unplanned trips to surface, and even lost-in-hole (LIH) scenarios. The root causes of problems during this project in the Mulichinco formation were determined to be hole cleaning, weight transfer, and vibration; this paper describes the evolution of drilling improvements based on real-time and post-well analyses. A holistic approach was necessary to understand the evolution and interaction of each aspect of the operation, from well planning to drilling the well. All information collected and analyses performed were shared with other involved parties to continue the improvement process. The effects of various changes that were implemented were evaluated, and those that had a positive effect were replicated where possible. During two years of tight sand well operations, the three primary problems included hole cleaning, weight transfer, and vibration. Hole cleaning was improved by closely monitoring the real-time equivalent circulating density (ECD) and torque and drag (T&D), and by adjusting the surface parameters accordingly. Comparing real-time data with the expected simulation outcomes helped to identify the optimum parameters to be used. At first, to mitigate vibration, vibration mechanisms were identified, and surface parameters were changed in an unsuccessful reduction attempt. It then became clear that the problems were associated with the BHA design, and simulations were necessary to identify the problems. Similarly, simulation results were complemented with real-time and recorded data analyses. The weight transfer problem was much more difficult to resolve. A wide variety of information was collected, including visual observation of abnormal wear in drillpipes, comparison of ROP in wells with different BHA designs, and simulations to determine the optimal positioning of the BHA and tubular components. Taking all of this information into account, adjustments were made, and weight transfer gradually improved. These combined improvements resulted in the elimination of LIH scenarios, reduction of unplanned trips caused by tool failures (primarily rotary steerable), and an average reduction of 55% of the time required to reach total depth (TD), from approximately 41.5 days to 18.5 days. The guidelines described in this paper contribute to the technical optimization of tight sands drilling because they can be used to implement a learning curve process that is applicable for similar operations elsewhere.