Simplifying Hydraulic Fracturing-Theory and Practice

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAlthough hydraulic fracturing is a routine stimulation technique in many parts of the world, it has seen limited use in areas such as Asia Pacific for example. Among the hurdles to fracturing in traditional non-frac markets is the common perception that fracs are expensive, risky, complex and difficult to design. This perception has been challenged in recent years by the promotion and technical validation of simplified fracturing treatments aimed, primarily, to address near-wellbore skin damage. The new approach, termed Skin Bypass Frac (SPF), is low cost, safe, simple, and easy to design. In fact, by careful fluid selection, these small treatments can be pumped from an offshore drilling rig using nothing more than cementing equipment. By simplifying fracturing to this degree, there is now a safer and more environmentally-friendly way to remediate skin damaged wells, without the implicit dangers of acidising.To date, this technique has been used in a number of diverse situations yet, despite its simplicity, it has yet to be practised on a widespread basis. Results indicate that if candidate selection is good, production increments can be significant, particularly in those wells with skin damage. To make candidate selection effortless, a set of criteria was developed to determine which wells would benefit the most. Parameters such as permeability, zone height, estimated skin, reservoir mobility, zone isolation and proximity to water were all considered in this selection model. This paper reviews the practical theory of using small simple frac treatments to improve productivity in damaged wells and wells with small sands where higher recovery rates are desired. The concept of LCP is discussed and a model is put forward to perform frac jobs with cement units, which may come to be known as universal pressure pumping units.