SPE Papers
SPE 84391 - Comparison of Two Low-Permeability Horizontal Devonian Projects in the Permian Basin with Competing Completion Techniques
J. R. Edgeman, SPE, BJ Services Company, USA and D. W. Walser, SPE, BJ Services Company, USA
Detailed production data from 32 horizontal Devonian wells in the Permian Basin was studied to determine if the impact of various completion methods might be distinguished from an existing reservoir overprint. Flowing transient pressure analysis was utilized to determine effective permeabilities, contributing lateral lengths, and respective drainage radii. Production and economic performance on each well were normalized for permeability, productive zone height, porosity, and initial static reservoir pressure, so that examinations into various completion processes would be more meaningful. Multiple physical parameters and controllable process variables were then plotted versus normalized net present value.
A fully coupled three-dimensional reservoir and wellbore simulator was employed to match historical results and extrapolate conclusions beyond the narrow confines of the two projects.
Some wells in the study were completed with cemented liners, and others completed with pre-drilled uncemented liners. A direct comparison is made between the two completion styles.
SPE 84392 - Valhall Field: Horizontal Well Stimulations "Acid vs. Proppant" and Best Practices for Fracture Optimization
Karen E. Olson SPE and Eivind Olsen SPE, BP Norway; Sami Haidar SPE Fracture Technologies; Alexandre Boulatsel SPE Schlumberger; Kristian Brekke SPE, PTI
Proppant fractures along the horizontal laterals in the Valhall Field have become a standard completion method for the last eight years with over 150 proppant fractures completed to date. The development of the flank regions of the Valhall Field began, with the first of 14 wells completions, in March 2003. Lateral lengths of up 2,000 meters will be drilled from two new platforms placed on the North and South edges of the field. The chalk formation in the flank regions is expected to be more competent then the crestal part of the field, so the question was raised as to whether fracturing should be done with acid or proppant. From a proppant fracturing perspective, each flank well will require between 10 to 14 prop fractures along its lateral requiring 2.5-3.7 Million pounds of proppant per well.Three different methods have been used to determine whether the wells should be acid or proppant fractured. These consist of reviewing the historical well performance, analytical and numerical modeling. All three methods clearly showed proppant fracturing was the preferred stimulation for the Valhall Field regardless of its location. Acid fracturing becomes the stimulation of choice only if the well does not come in contact with enough OOIP (e.g. 5 MMSTB) to justify the proppant fractures.
Proppant fracturing is expensive, so in conjunction with identifying the best stimulation method for the flank region, optimization with respect to fracture spacing along the horizontal lateral, fracture length and width have been numerically modeled for both the crestal and flank wells. This is an evolving process that should be considered an industry "Best Practice" as it enables real time optimization of 'prop' fracturing along a horizontal lateral during the drilling and completion phase. Since the start of this "Best Practice" in 2002, the wells stimulated in the crestal part of the Valhall Field have had the highest productivity in the field's history.
