New Solids-Free, High Density Brines Solve Many Workover and Completion Problems
Authors: Wendorff C.L. 
Published: December 2007

This paper was prepared for the Society of Petroleum Engineers of AIME Symposium on Formation Damage Control, to be held in New Orleans, La., Feb. 7–8, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Mixtures of calcium bromide, calcium chloride and water provide a solids-free brine with densities up to 15.1 ppg. For the first time gravel packing, sand consolidation and other types of workovers can be done with clear non-damaging fluids having these very high n-sities. Like calcium chloride, the calcium bromide-calcium chloride mixtures have very natural corrosion rates. These rates can b lowered by the addition of an inhibitor. Acid soluble additives to reduce fluid loss and increase viscosity are available to modify these heavy brines for use in almost any well situation. In addition, they are both toxicologically and ecologically safe to use. Data showing the properties of calcium bromide-calcium chloride brines and brines modified with additives will be presented. The ways these heavy brine systems may be used to solve well problems will also be discussed.

Drilling fluids are often used to maintain control during perforating, completion, or workover operations. When these fluids are used opposite highly permeable zones, extensive or even irrepairable formation damage can result. Such damage can be minimized or overcome by use of new heavy brine completion fluids weighted with calcium chloride and calcium bromide.

Introduction

Drilling fluids are formulated to plate out and plug the formation face so that only small volumes of fluids are lost during drilling. The filter cake formed from many drilling fluids is frequently difficult if not impossible to remove. The fluids themselves are sometimes highly alkaline and pH may be as high as 12–14. This causes precipitation of insoluble hydroxides along the filtrating path. The point is that drilling fluids are primarily designed to increase drilling efficiency. The technology of these fluids is well advanced and as a result drilling is faster, requires less horsepower, and in some cases permits drilling to progress under conditions which would have been impossible to overcome a few years ago. While strides have been made to reduce the damage drilling fluids do to the producing zone, nevertheless some of the properties intentionally built into these fluids are diametrically opposed to the ideal properties of a completion or workover fluid.

Drilling fluids are also used as packer fluids.