Operational Decision Making for Stuck-Pipe Incidents in the Gulf of Mexico: A Risk Economics Approach

Abstract

Summary The purpose of this study was to identify the most effective methods to free stuck pipe and to quantify the success rates of these methods under various wellbore conditions on the basis of historical data. This information has been integrated into a decision-making flow chart based on risk economics to determine when to begin and terminate operations to free stuck pipe. Introduction The Offshore Producing Div. at Texaco U.S.A. has developed a standard operational procedure for handling stuck pipe. The procedure involves spotting a diesel-based pill (DBP) if the pipe cannot be worked or jarred free in the first few hours after sticking. If the DBP fails to free the pipe after about 24 hours, the pipe usually is backed off above the free point and we try to free the pipe with fishing jars. Until now, we made these decisions without supporting data to indicate whether the benefits of operations to free stuck pipe justified the cost. Although the costs of pipe-freeing procedures usually are small compared with sidetracking costs, they are significant. Attempts to free stuck pipe by spotting pills or jarring usually require several rig days and can cost hundreds of thousands of dollars. These operations should be implemented only if their potential benefits outweigh their costs. The primary objectives of this study were to quantify the probabilities of success for various methods of freeing stuck pipe and to formulate a generic stuck-pipe decision-making process based on risk economics. When fishing operations begin, a certain cost is associated with freeing the pipe successfully, and a higher cost is associated with an unsuccessful fishing attempt that leads to plugback and sidetrack. This situation (two possible outcomes with known costs and known probabilities) lends itself well to expected value analysis. In this study, the expected cost of attempts to free stuck pipe is called risked fishing cost (RFC).

The radial cutting torch device application due to drill string sticking

“…Generally, if there is no improvement after 72 hours, it is better to stop wasting time and money and to move on searching for another way to free the stuck pipe. Definitely, one of the best ways to solve this problem that includes the stuck pipe severing is to utilize the RCT cutting tool (Shivers and Domangue, 1993).…”

A Model for Early Detection of Stuck Pipe Using Random Forest Algorithm

“…Differential pressure causes stuck pipe when drill string is pressing against the wellbore due to difference between downhole pressure and pore pressure, particularly in the permeable formations. Understanding stuck pipe mechanisms and their typical impact on drilling parameters can help not only in early detection of the trends, but also in proactively deploying mitigation strategies (Shadizadeh et al 2010;Shivers et al 1993). There have been a few ways to minimize the stuck pipe risks in the drilling industry, such as BHA con gurations optimization to reduce the con ict between BHA and wellbore geometry, mud properties optimization to enhance the hole cleaning capability and reduce the friction between drill string and wellbore, rig crew training to reduce human errors in remediation operations and increase the awareness of potential stuck pipe.…”

Investigation on Releasing of a Stuck Drill String by Means of a Mechanical Jar

“…Thus, the task of developing new technological solutions and sophisticated technical means to release the drill string sticking remains relevant [6].…”