Proposed Methodology and Application of Statistical Analysis Methods on MPD Surface Back Pressure Control System's Performance Evaluation in Extended Reach Drilling (ERD) Wells

Abstract

Over the years, the performance of MPD systems is often called into question when it comes to Surface Back Pressure (SBP) applications to maintain the desired downhole pressure set point, thus eroding the confidence level in applying constant bottomhole pressures at target depths – whether at bit or a fixed depth. In this paper, the performance of various MPD systems is evaluated utilizing statistical analysis, including offline Change Point (CP) inference and Regression analysis on the downhole Pressure While Drilling (PWD) data as a result of the SBP applied during drilling operations. The paper also proposes an objective methodology in the evaluation process, minimizing the influence of various MPD systems’ operating philosophies. The main criteria of the evaluation process are to determine the variances between the modelled and actual MPD setpoint downhole pressure against PWD data at target depth, depending on various operation types. In order to reduce the influence of varying operating philosophies across different MPD systems, the methodology proposed focuses on drilling operations and common data across wells. Analytical methods, including offline Change Point Analysis, are used to identify the sequence of events, operation types and pumps-off events. The trending of ESD and ECD are then determined based on operation categories. Finally, the variances and standard deviation between PWD data and setpoint EMWs are determined using regression analysis as well as normal median and mean values analysis to evaluate the performance of the MPD system and also to determine factors that could affect the performance of the system.