Solids-Free, High-Density Brines for Packer-Fluid Applications

Abstract

A worldwide review of workover operations indicated extremely high costs associated with recovery of tubing stuck in settled mud solids. High density water-base or oil-base muds are not stable suspensions when left static in a well for a long time. High temperatures and/or contamination of these muds with the produced gas and oil destroys the initial suspension properties and allow mud solids and weighting materials to settle on top of the packer and around the tubing. Expensive washover and fishing operations are then performed. During the washover, more costly complications such as: twist off or stuck washover pipes, casing leaks, blowouts, formation damage, etc., could develop. When such complications occur many wells have to be plugged and abandoned. Most of these problems could be eliminated by utilizing solids-free packer fluids. Single salt and blends of high density brines have been tested to determine their corrosive nature. An inorganic corrosion inhibitor was developed and field tested. Laboratory and field data generated are presented along with the authors' conclusions. In the last few years, many deep, high temperature and high pressure wells in the Gulf of Mexico have been successfully completed with inhibited high density brines, which were also left as packermore » fluids. Some of these wells were worked over, tubing and packers were retrieved easily and no significant corrosion was observed.« less