Mature Assets to Unconventional Reservoirs: CT Deployed Hydrajet (Abrasive) Perforating Offers Many Stimulation Alternatives
Authors: McDaniel Billy W 
Published: May 2016

Starting in the early 2000's, we began to see increasing use of Hydrajetting for perforating as a companion to multi-stage fracturing operations. Bundling it within this larger service operation provides for an opportunity to overcome the added costs of using coiled tubing (CT) by developing methods that would allow the CT to stay in the wellbore while performing perforating only minutes prior to fracturing through the new perfs. This can be accomplished by using several different methods for isolating the zone just stimulated without tripping the CT string.

This is most cost-effective where the well does not still have a rig, and even more beneficial if the other competitive options for stimulation would also require a stand-by CT string (for screenout, or in case of premature plug setting). More recently, the development of newer types of jetting tools has proven to bean effective method to revive higher perm zones that have recovered very little of the Oil in Place (OIP), especially where well architecture such as slotted liners and bare open hole completions have few or no competitive stimulation options. Several interactions of improving tool life have been accomplished during the past decade, and the need for less horsepower for effective multi-stage fracturing operations allows much smaller footprints than for the commonly applied North American style multi-stage fracturing operations. Also, in countries where any type of explosive charge is very highly guarded and regulated, CT Hydrajet perforating has seen significant application as a stand-alone well completion component.

This paper will briefly review the tool advancements and highlight the various applications where Hydrajetted perforations empower various initial completion stimulation methods/techniques as well as several different re-frac recompletion successes from moderate permeability formations to nanodarcy sands and resource reservoirs. Also, some general comparisons of costs vs. the more commonly used perforating/stimulation/completion approaches will be provided, as well as discussion of well production comparisons where available.

Introduction

This paper will first provide a historical background for perspective on conventional shape charge perforating, then review/compare the benefits and limitations of CT deployed application for abrasive jet perforating. Next, the discussion will center on the revolutionary process introduced in the late 1990's (Surjaatmadja 1998; Eberhard et al. 2000) which began the modern expansion of Hydrajet perforating technology and application. This process started experiencing increased applications into the early 2000's and can be classified as Hydrajet-Assisted Fracturing (HJAF), where all the proppant slurry is pumped through jet nozzles immediately following the Hydrajet perforating stage with no interruption to pumping and repeated multiple times to provide multi-stage fracturing as it is pulled step-wise through a horizontal well. It was introduced before horizontal wells were common, and is still in use today.

The third section will cover the process of multistage continuous applications of Hydrajet perforating through CT and then pumping the fracturing slurry down the annulus of the CT and the casing with an immediate isolation of the fractured interval and thereafter repeating this process many times as the CT moves up the hole. This achieves significant time savings as only one CT deployment will perf/stimulate/isolate multiple intervals in either vertical or horizontal completions. Several variations of this process are discussed that, in general, perforate using CT, then fracturing operations are pumped down the annulus, then the process is repeated up hole several times. Various methods to isolate the current fracturing zone from those downhole are employed without removing the CT from the wellbore.

In the final section, the application as a CT deployed stand-alone perforating service process, including case histories in conventional completions and unconventional formation well completions, is presented.