Cementing: Bridging the Gap From Laboratory Results to Field Operations
Authors: Arnold Edwin S. 
Published: December 2007

Fundamental mud-displacement studies have used what was considered a realistic simulation of well conditions, but application of the technology in the field is difficult because of the U-tube effect in an actual well. There are more chances for error in the field because the job depends on many people who may not understand the fundamentals of the process.

Introduction

An effective primary cement job is the first and vital step toward a good well completion. The primary cement job is unique since it offers the best chance to displace the annular mud effectively with a cement slurry. Today's cement jobs may have to withstand higher formation pressures than those of a generation ago, and may require the isolation of several potential producing zones.

Cementing has long been considered an art rather than a science. Yet the literature on the application of scientific principles to advance the state of the art dates back more than 50 years. There has been much research to solve specific problems and to develop improved cements, additives, and products to meet a wide variety of needs. Such improvements are usually tangible and are disseminated throughout the industry by advertising and sales forces. The following discussion assumes selection of a suitable cement and is devoted to the other phases of the job.

Three main problems make up the gap that exists between laboratory research and field operations:a general lack of knowledge among field personnel concerning basic fundamentals that have been established by research,the failure to view the mud displacement process from the bottom of the well, andthe need to overcome present shortcomings in the execution of cementing jobs.

The purpose of this paper is not to solve the may problems involved, but to bring them to light. It is hoped that they may be reduced or eliminated by further research, testing, training, improved equipment, and greater dissemination of the available technology to all involved in the planning and execution of cementing operations.

Lack of Fundamental Knowledge

Research into the fundamentals of the cementing process has been continuing over the years and has reached ever higher levels of accomplishment. Yet it is obvious that many employees in the field, working for companies engaged in continuing research, are not aware of the importance of the work or of the main conclusions. There are others new to the industry who have not yet been exposed to cementing operations. Finally, there are engineers in management, as well as nontechnical people, who, because of their many duties, have not kept up with the state of the art. This group may find themselves making decisions on the basis of the cementing lore they learned in earlier days. These situations contribute to the difficulty in applying today's technology to field operations.

For those who have not followed the progress of cementing technology, a good background can be obtained from two excellent summaries on oil- and gas- well cementing by Smith in 1976, and by Suman and Ellis in 1977. Both works have extensive bibliographies. The title of this paper, when selected, was considered an original thought.

JPT

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