Optimizing Milling-ROP by Applying the Concept of Mechanical Specific Energy (MSE)

摘要

The concept of mechanical specific energy (MSE) was used to optimize the rate of penetration (ROP) during casing milling, while abandoning a gas well in Northern Germany. MSE is a well studied concept and is described in many publications, however this project is one of the rare attempts to systematically optimize ROP during milling of casing. Casing milling can be one of the most time-consuming, and therefore expensive activities during drilling, workover and abandonment operations. In order to reduce cost, a fast and efficient milling process is necessaty. One way to enhance optimization of ROP while milling casing is through the identification of MSE trends in real time. Even though the concept of MSE requires dedication and effort by the drill crew, it is a practical tool, which often comes free of charge. MSE works with surface data, which is already recorded on most modern rigs. Its application does often not require additional cost, but rather human effort. Since the initial work of R. Teale from the year 1965, the concept of MSE has been a simple but also comprehensive trending tool to optimize drilling in real time. Even though the concept was initially intended to measure the efficiency of rock destruction, it can also assist in optimizing ROP while milling casing. For a case well in Germany, the rig crew was trained to understand the concept of MSE and to use it to improve decision making to enhance milling-ROP in real time. The execution of the project showed that by analyzing trends in MSE and conducting MSE tests a 锝?4% higher milling-ROP compared to data from an offset well was achieved. In addition to that, a 12% higher maximum ROP was recorded. Furthermore, the concept of MSE helped to identify the optimum operating parameters in a faster way and to keep focus on maximizing ROP during the relatively monotonous process of casing milling. This has been the first time for the operator to introduce a comprehensive tool to detect inefficiencies while milling casing.