Chapter 7: Matrix Acidizing

This chapter is organized to help perform acidizing on a well candidate in a logical step-by-step process and then select and execute an appropriate chemical treatment for the oil/gas well. The guidelines are practical in intent and avoid the more complicated acid reaction chemistries, although such investigations and the use of geochemical models are recommended for more complicated formations or reservoir conditions. Effective acidizing is guided by practical limits in volumes and types of acid and procedures so as to achieve an optimum removal of the formation damage around the wellbore.

Most of this chapter is an outgrowth of field case studies and of concepts derived from experimental testing and research. Justification for the practices and recommendations proposed herein are contained in the referenced documents. The reader is referred to the author’s previous papers on matrix acidizing for references published before 1990. Concepts and techniques presented have been examined during repeated presentation of the Society of Petroleum Engineering (SPE) Short Course titled “Matrix Acidizing to Improve Well Performance.” ¹  Recent research has fine-tuned many of the concepts and acid types that are incorporated into proprietary software of various service companies. These programs are available through service company stimulation specialists who can assist with particular formation characteristics and reservoir conditions. The reader should use this chapter as an introduction to significant and necessary concepts and practices. Improved procedures and products can be selected by the company engineer in partnership with the stimulation specialist using proprietary software. The objective in the following discussion is to provide reasonable procedures and guidelines and to offer cautions suggested by particular formation compositions and reservoir conditions.