This paper describes the use of reservoir simulation to refine reservoir descriptions of the Bakken Shale for predictions of single well and multiple well performance. The descriptions were achieved by matching drawdown, buildup, and interference data from horizontal wells in the Buckhorn Field, McKenzie County, North Dakota, Figure 1. Reservoir descriptions - matrix and fracture storativities, ϕCtH, and matrix and fracture permeability-thickness products, KmH and KfH -- were developed for both single well and multi-well interference data. More than one description could be found to match single well data; however, only one description was found which matched all the data. The best match of long term production interference data was obtained with a dual porosity description that included anisotropic, stress-sensitive permeability. In the dual porosity model, both microgeneration fractures and enhanced or extension fractures were modeled with a lumped description. The permeability anisotropy for this lumped fracture system was approximately 4 to 1 with the maximum permeability direction in the northern Buckhorn area being east-to-west. Bakken Shale porosity was determined to be 2 to 3 % with one-tenth of that volume or 0.2% being in microfractures. The ratio of fracture to matrix permeability was 100 to 1 with an effective permeability for the fracture system of 0.6 md at maximum net confining stress. It is believed that silt-stones and dolomites adjacent to the Bakken Shales make a significant contribution to the oil production through the extension fracture system.

The Prudhoe Bay field is the largest accumulation of oil and gas in North America. Because of the size, and the fact that it produces from multiple mechanisms including lean gas cycling, gravity drainage, pattern waterfloods, pattern MI / WAG injection and gas cap water injection for pressure maintenance, a full-field model (FFM) with a rigorous surface pipeline network and facilities model is necessary to answer many depletion planning questions and to evaluate the benefits of largescale or field-wide projects. With additional reservoir description data and production history, the opportunity existed to use current software and hardware to build an improved model. In 2005 an effort began to build a new FFM, including both geocellular and simulation models. This paper discusses the issues addressed at the start of the rebuild in preparation for the history match, the history matching effort, and the transition to predictive runs. Preparation for the history match included setting the objectives for the model, the grid design, generating pseudo relative permeability curves, and implementing parallel processing. The key parameters and data used to obtain a history match are discussed, as are the issues and methodology utilized in constructing predictive cases. Some of the key interactions with the parallel geologic model construction are also discussed. It was demonstrated that a compositional model with approximately 1 million active cells and over 650,000 non-neighbor connections associated with over 1000 structural faults could be run and history matched in a commercial parallel reservoir simulator in a reasonable time. With approximately 25 BSTB of oil, 46 TSCF of gas in place, and over 2500 historical wells, the challenge of building a fullfield model for a field the size of Prudhoe Bay was daunting. A project of this magnitude required excellent up-front preparation and cross-discipline coordination. Introduction The current full-field simulation model of the Prudhoe Bay Field was built in 1995. Due to the size of the field, as well as hardware and software limitations at that time, the simulation grid was very coarse with 60-acre (1617ft X 1617ft) grid blocks, making areal discretization of faults, wells and waterflood/MI injection patterns problematic. As the oil column thins and remaining targets shrink, a model with greater resolution for future project evaluations was required. The decision was taken by the major partner companies to build a new simulation model based upon a new 3D geological and petrophysical model, to take advantage of better hardware, software and workflows. The rebuild effort started in January, 2005. Initially the focus of the work was on the geocellular model build. However, many aspects of the simulation model had to be set before final delivery of the static description to avoid delay of the history matching process. This paper discusses the work that was done in preparation for the history match and the history matching process and results. There is also discussion of the transition and calibration from history to predictive mode.

TX 75083-3836 USA. ABS1RACTPerforation design is an important aspect of the completion of production and injection wells. Significant penalties can be incurred both through productivity loss or additional perforation costs if the design is not accurately optimized. These penalties are especially severe in the case of high-rate gas wells.The Well Perforation Performance Model (pERF) was developed as a collaboration between SSI, London and BP Exploration, Aberdeen. It allows different perforating methods to be evaluated and compared to select the ideal gun and charge for a given perforation job.A major technical feature of the program is the finite element simulator, which allows accurate modelling of complex geometries. It can analyze great detail on small computers.The program allows the analysis to carried out in detail, using a state-of-the-art finite-element simulator, or more rapidly using a set of industry-standard nomographs. A database of gun and charge characteristics is provided, which records the results of API laboratory tests, so that typical perforating problems can easily be set up.The results, in terms ofa productivity index or flow efficiency, can be viewed graphically as a function of the References and illustrations at end of paper. main physical parameters, including: Shot Density, Perforation Length and Diameter, Phasing, Damage and Compaction, Gravel Packing.Comparisons are provided against earlierpublished theoretical and experimental work, demonstrating improved accuracy and usability of the technology.