Elimination of Errors in Cement Displacement Volumes and Plug Bump-Plug Indicator System

Abstract

This paper describes the development and deployment of a new method of determining the physical location of a top cementing plug in a subsea casing string. Typically, the position of the top plug is approximated based on the calculated volume of the string, which can often vary significantly from actual casing volume, especially in long, heavy subsea casing intervals.Such discrepancies can create major problems during primary cementing operations, including failure to bump the top plug or potential overdisplacement of cement. The former tends to increase subsequent drillout times; the latter may result in contaminated cement in the shoe track.After review of the problems, the operator in the region concluded that utilizing the described technology, the Plug Indicator System (PIS), was warranted. The PIS was expected to facilitate more effective primary cementing operations by mitigating these risks, thereby reducing nonproductive time (NPT) and associated costs and avoiding expensive remedial operations.This paper reviews and helps familiarize the reader with the problems associated with subsea casing primary cementing operations. A case history of the PIS and its successful conclusion is presented.