Toxicity and Performance Testing of Non-Oil Spotting Fluid for Differentially Stuck Pipe

Abstract

Differentially pressured stuck pipe is a serious problem in the Gulf of Mexico and other areas of the world which results in costly and lengthy time delays. For years diesel oil, mineral oil, and mixtures of these oils with surfactants, clays, and asphalts have been spotted to help alleviate differentially pressured stuck pipe. With the advent of the Environmental Protection Agency's National Pollutant Discharge Elimination System (NPDES) General Permit on July 2, 1986 and the ending of the Diesel Pill Monitoring Program (DPMP) on September 30, 1987 the use of these conventional spotting fluids is becoming more stringently controlled in the offshore waters of the United States. In fact, after the use of conventional spotting fluids, the entire mud system may have to be sent ashore for disposal since offshore discharge is not allowed. In an effort to provide an environmentally acceptable alternative to oil based spotting fluids, a laboratory procedure was developed and used to measure the ability of various chemicals to free a metal bob held in a filter cake by a differential pressure. After the effective additives were identified, a few were selected for bioassay. One water-soluble agent, in addition to being highly effective in the stuck pipe simulation test, had a very low order of toxicity. This material was formulated into an experimental spotting fluid that successfully freed a differentially stuck drill string in the Gulf of Mexico. The development of a non-oil, low toxic spotting fluid has provided a suitable alternative to conventional spotting fluids resulting in an effective and environmentally safe way to combat differential pressure sticking of the drill string.

A New Approach for Estimating Free Point in Fishing of Stuck Pipe using Artificial Neural Network

“…In the case of spotting and pumping pills, Halliday and Clapper in 1989 [4] specified the features of spotting fluid as to be 1) with low toxicity, 2) water miscibility, 3) adequate barite suspension, 4) no adverse effects, 5) moderate cost.…”

“…Applying the above procedure in this work resulted in significant improvement in the performance of the ANN. In this study, all input and output data are normalized between [-1, 1] by the function: (4) Where y, y max andy min arenormalized values, 1 and -1 respectively.…”

Water-Based Alternatives to Oil-Based Muds: Do They Actually Exist?

“…While this application must represent the first use of a 2-phase polyglycol system, this feature seems to have gone unrecognized. Deliberate application of 2-phase polylglycols systems as drilling fluids based on Cloud Point Temperature or phase separation temperature was first claimed in 1987 11 and by 1988 a new generation of polyglycols made from propylene oxide were in commercial use freeing differentially stuck pipe 12,13 . This new generation of polyglycols was also non-toxic and by 1991 the benefits of this chemistry with respect to lubrication, minimizing shale swelling, bit balling, differential sticking as well as release of differentially stuck pipe had been recognized 14 .…”