This paper reviews a unique, relatively new stimulation process that uses dynamic fluid energy (instead of mechanical methods) to isolate treatment fluid flow to a specific fracture point along the wellbore. A process of hydrajet-fracturing has been developed by merging four existing technologies: hydrajetting, hydraulic fracturing, jet pump technology, and dual-path fluid injection. These have been meshed to create a method whereby a wellbore is perforated (if necessary) and a fracture is initiated and placed accurately at a specific location, and then soon repeated at another chosen location uphole, or closer to the heel when in a lateral wellbore. The process was later expanded as a hydrojet-squeeze stimulation method also, even to the point of applying both of these applications while stimulating a single wellbore. This process employs two independent fluid streams: one in the treating string and another in the annulus. As these fluid paths will be supplied with separate pumping equipment, we have the option to instantaneously alter the downhole mixture that is being used to treat the formation at the current location of the jetting tool. An additional use of this two-stream feature is the capability to pump two different fluids that can be mixed downhole with a tremendously high energy to form a homogenous mixture at the fracture entry point, even creating foamed fluids insitu for some applications. This technique has been used to stimulate more than 50 horizontal or highly deviated wells (and a few vertical wells) as of the preparation of this paper, both proppant-laden fractures and fracture acidizing treatments. On average, more than 7 fractures were placed along a typical horizontal wellbore, typically several hundred feet apart without the use of mechanical sealing equipment. Additionally, numerous horizontal wells with higher permeabilities have been stimulated using the hydrajet-squeeze process alone. The diversion process follows a dynamic isolation approach that uses a high-velocity, high-energy jetted fluid. The process was originally developed for its unique stimulation capabilities in openhole horizontal wells, but has been extended to wells that have cemented or non-cemented liners, whether vertical, deviated, or horizontal and even to multilateral completions (or recompletions). This paper offers insight into many of these treatments, including the different well situations, design considerations, operations, and available results of the treatments. Possible unconventional approaches using this concept and a unique implementation in the field are also discussed. Introduction When an operator considers a horizontal completion in a low-permeability carbonate or sandstone reservoir, cost containment becomes a prime drilling and completion consideration. For many recent and currently planned projects throughout the world, the opportunity for openhole horizontals to give increased production per completion dollar economically may be what justifies the development of a new field or additional drilling in an existing field. Also, the re-entry of older vertical wells for horizontal recompletions may dictate that the completion is openhole because of hole-size limitations. The global reality that our industry seems slow to accept is that horizontal completions in low-permeability reservoirs usually require significant stimulation for achieving truly economic production rates. Many horizontal-drilling programs have been based on often incorrect assumptionsthat long openhole laterals will avoid the need for expensive stimulation treatments normally required for economic vertical-well completions in that reservoir. Hydrojetting, the use of water under high pressure, is a well known technique that many industries use to perform different tasks.1 These tasks include cleaning and preparing surfaces, placing cements, drilling, cutting, slotting, perforating, machining, grouting, mining, and even household uses such as car washing and dental hygiene. Sand-laden fluids can be used, or cavitating jets may be required. Jetting pressures have ranged from a few hundred psi to 60,000 psi.

Key Production Co. began using short-radius, moderate length openhole horizontal lateral recompletions in re-entries of wells in a limestone/dolomite reservoir in northwest Texas. They found that a few wells needed some type of stimulation to achieve optimum production rates. A dual lateral (90° opposed) was drilled on one re-entry to improve production performance. This well was in an area of the field with below-average reservoir quality, and production rates were still disappointing even with two lateral sections. Fracture acidizing was the most likely method to achieve the degree of stimulation needed. There was concern that this might lead to unwanted communication with the aquifer zone below the oil column. Conventional stimulation methods could not achieve multiple, well-spaced, limited-sized fractures. The operator used a new hydrajet-fracturing technology that has shown a very high success rate in other areas to achieve the stimulation needed for this well, and at acceptable cost. Six separate fractures were placed at selected locations along each of the two lateral sections (12 distinct fractures) in less than 8 hours from first pumping to final displacement. The resulting production rates far exceeded the operator's expectations. This paper presents a brief review of the hydrajet-fracturing stimulation process and specific details related to its highly successful application in this Level 1 dual-lateral completion. Background In 1998, Key Production Co. acquired the production and drilling rights to several leases in Hardeman County, Texas (Fig. 1). Of specific interest is production from the Meramec and the Chappel formations. In this region, the Meramec is primarily a limestone formation, and the Chappel is a moderate- to low-permeability limestone/dolomite reservoir that produces oil from approximately 7,800 to 8,200 ft and overlies the Ellenberger Aquifer. Typically, where the Chappel has been more completely dolomitized, there is better permeability and porosity, yielding higher production rates. Primarily, conventional vertical well completions have been employed throughout this field. Two of the more common completion methods used are represented inFigs. 2 and 3. Both of these completion plans drilled a 12 1/4-in. hole to approximately 500 ft and cemented in 8 5/8-in. surface pipe. As shown in Fig. 2, some wells were then drilled into the Chappel formation until porosity was found. If a drill stem test (DST) indicated oil was present, the 5 1/2-in. casing was run with a formation packer shoe on bottom. The packer shoe was set in the tight lime above the porosity and the casing was cemented. The shoe was drilled out and the well completed opehnole, typically without any type of stimulation treatment. Another common completion method used (Fig. 3) continued drilling into the primary-hole well into the Chappel lime 100 to 400 ft, depending on the local geology of the reservoir. The 5.5-in. casing was run to total depth (TD) and cemented back to 500 feet above the Meramec. These wells were completed by perforating and, if required, acid stimulated. From the early to mid-1980s, some wellbores were plugged and abandoned as dry holes with no casing being set. After studying the geology of the reservoir, Key Production Co. believed that some of these locations could be re-entered and economic production rates achieved using short-radius, moderate-length, openhole horizontal laterals. Fig. 4 is a schematic representing one of the abandoned wellbores recompleted as a horizontal well. In a part of the field considered low-quality, the operator decided to recomplete one of the abandoned wellbores in the Chappel lime as a Level 1 dual-lateral completion, with the laterals at similar depths and opposed by 90° (Fig. 5). The laterals were approximately 780 and 800 ft in length. After completing the second lateral and swabbing/flow-testing the well for two weeks, the team decided that some form of production enhancement treatment was needed to achieve optimum production rates.