Hydraulic fracturing of horizontal wells in shale gas reservoirs is now an established, commercially successful technique. The evolution of the completion technique has reached the point that numerous stimulation stages through multiple perforation clusters in wellbores with some form of annular isolation is now an accepted practice. The objective is to place multiple closely spaced hydraulic fractures. This has proven to be a viable development strategy for many shale reservoirs in North America. To further enhance the recovery factor in these ultra low permeability reservoirs simultaneously hydraulically fracturing of adjacent wellbore is increasingly being tested. Most of the time this is performed in horizontal wellbores paralleling each other. The goal is to create hydraulic fractures more closely spaced than can be achieved from a single wellbore. When real time microseismic monitoring of the stimulation treatments is incorporated changes can be made "On-the-Fly" to improve the effective stimulated reservoir volume. Continental Resources has employed simultaneous hydraulic fracturing as a development strategy for their Woodford Shale acreage in the Arkoma Basin of Eastern Oklahoma. To monitor the effectiveness of the stimulations geophones have been deployed into horizontal wellbores to record microseismic events when offsetting vertical wellbores are unavailable. Cased hole sonic logs have also been run to quantify cement bond quality, estimate stress variation along the lateral, and to pick optimum perforating points. This paper reviews the methodology employed in the completion design and process. The impact of the simultaneous stimulations and geologic structure on the fracture geometry are shown as well as the impact on well productivity.

Horizontal well completions in the Granite Wash formations of the Anadarko basin in Western Oklahoma and the Texas Panhandle approximately doubled year on year since 2006. During this period, the evolution of horizontal well completion and stimulation practices coupled with diligent identification and selection of lateral landing in high reservoir quality has resulted in significant production gains. Various techniques utilizing large samples of well production and completion/stimulation parameters are common in high well volume resource plays to determine well performance drivers. Several studies have been done in the Granite Wash, mostly in vertical wells with multiple pay zones co-mingled. Prior studies are isolated to smaller well samples or are focused on a single well completion strategy. This paper investigates two different areas of the Granite Wash consisting of seventy three horizontal wells in Western Oklahoma and one hundred sixty five horizontal wells in the Texas Panhandle completed in 2007 through the end of 2009. The objective is correlating completion and stimulation parameters along with lateral length with production trends. First, an overview of production trends and average probable production in different regions is presented. The second half of the paper evaluates completion and stimulation parameters including but not limited to fluid and proppant pumped per unit length of completed interval, total fluid, total proppants, lateral length, number of frac stages and average proppant concentration.

The multi-zone Granite Wash is a mature vertical well play extending across 6 counties in the Texas Panhandle and Western Oklahoma. The laterally and vertically extensive formations were developed with close spaced vertical wells for several decades. In the last five years, almost all development has been horizontal, initially adapting drilling and completion technologies from shale gas development. With over 200 million barrels of proven Granite Wash reserves and low US natural gas prices, Anadarko basin E & P efforts are migrating towards higher rates of return from Granite Wash light oil, gas condensate and natural gas liquids. Driven by horizontal drilling and modern completion and fracturing techniques, horizontal well count and hydrocarbon liquid production have more than tripled over the last 4 years in this active U.S. mid-continent play.Unlike typical sandstone reservoirs, the Granite Wash has complex mineralogy including quartz, potassium and sodium feldspars, illite, chlorite, dolomite and calcite. Depositional environments range from near shoreline to continental slope events to deep marine. Many of the targets consist of compartmentalized sub-marine fan deposition. Due to high level of reservoir heterogeneity and GOR, it is difficult to characterize reservoir property changes between fields and horizons. Prior production driver studies on vertical wells in the Granite Wash did focus on both reservoir and completion parameters. The bulk of horizontal studies are limited to completions and stimulation without rigorous investigation of stratigraphic and reservoir quality variation. This paper correlates well performance with completion and fracturing practices in well samples of similar geographic and stratigraphic position, determined from public domain well, completion and well and log data.Using the large enormous public database of vertical wells, a three-dimensional sub-surface model of the reservoir is built for three geographic areas with multiple stratigraphic benches to reduce sample variation of reservoir quality. Reservoir quality is defined from petrophysical properties that affect the productivity of the well including but not limited to porosity, permeability, saturations and rock mineralogy, and accordingly, property distribution models are built for each property across study areas. Stimulation parameters investigated include, but are not limited to lateral length, number of fracturing stages, and normalized fluid and proppant volumes. Reservoir quality from the three dimensional model and parameters from the stimulation database are then correlated with well production to identify both stimulation and reservoir production drivers. The result sought is improved conclusions and recommendations for completion and stimulation in specific geographic areas and stratigraphic benches.

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