Analysis of Wellbore Stability Management and Surveying Time When Using MWD Survey RPM on Cessation Method in Drilling Operations

摘要

This paper explores various case studies to evaluate how an innovative methodology for sending MWD surveys up hole, based on cessation of surface RPM rather than variations of mud flow rate, helps drilling operations become more cost effective, decreasing wellbore stability & HSE risks, reducing surveying time and optimizing connection procedures. Conventional surveys are taken by recycling the mud pumps. Mud flow is brought to below the MWD turn-on rate in order to switch off the tool and trigger the survey, and then the flow is increased to above the turn-on rate and the survey is sent to surface. Surveys based on RPM cessation use a different technique that allows the MWD tool to take the survey and to transmit it to the surface acquision system when it detects that the rotation has being stopped, allowing the mud flow to remain unchanged and removing the need to recycle the pumps. Various distinct applications were analyzed in terms of MWD surveying time, wellbore stability and stuck pipe risks to evaluate the impact of this new approach in drilling operations. The cases analyzed deal with the following aspects: reduction of stuck pipe events in projects with high risk wellbore stability issues, ECD and pressure management in MPD projects, anti-collision avoidance and overall reduction of rig time for projects taking MWD surveys before connection. It was concluded that more and more phases of a well construction have seen the benefit of this methodology as it has greatly contributed to the efficiency of drilling operations and in some of the cases allowing the fulfillment of the well objectives by the significant reduction of drilling risks, in comparison with the conventional way to take MWD surveys. This is a novel approach to take MWD surveys and send them up-hole; very little has been written in industry literature about how its application enhances the reduction of key drilling challenges such as reduction of stuck pipe events. This will allow operators and contractors to push the envelope even further, in scenarios where extra fluctuations in the mud flow are adding significant financial or HSE risks.