Development and Application of Improved Reservoir Characterization for Optimizing Screenless Fracturing in the Gas Condensate Jauf Reservoir, Saudi Arabia

Abstract

Abstract Efficient field development requires excellent quality reservoir and field data to be used in the reservoir and production models. Hence, improved reservoir characterization is very important for obtaining optimal gas recovery. This paper presents the results of development of improved reservoir characterization and sand prediction models leading to successful hydraulic fracturing treatments. These models were applied in the Jauf sandstone reservoir in the Ghawar Field, Saudi Arabia. Two aspects were thoroughly investigated and improved upon in the process of our study. First, fracturing technique using the best possible combination of fluid, proppant, and perforation interval was developed that covers most of the vertical layers and creates deep conductive lateral penetration. Second, screenless completing technique was developed to minimize sand production. Correct proppant type and size, chemical agent, and choice, extent, and placement of perforation type and interval were developed to optimize this process. Solution to sand production problem was developed because of the Jauf sandstone reservoir quality, which has a high tendency to produce sand against moderate to strong drawdown pressures. A new sanding model was also built to assist in the completion strategy. This model differentiates between layers that have strong sanding tendency and layers that are competent. Finally, sand-free production rate was reached and maintained by evaluating post-fracture performance. In order to optimize the completions in the Jauf reservoir, development of a comprehensive data set was required. Improved petrophysical and mechanical properties models, using cores, logs, geological and geophysical properties, and field performance, were developed. Calibration of the models using up-to-date field responses where possible was performed. Production forecasts were generated from the data set to characterize well quality. Utilizing this comprehensive data set with the new completion model developed to address the issues of gas optimization and sand production led to successful optimized screenless completion techniques. Detailed description of pre-fracture data preparation and post-fracture data analysis are presented in this paper. Development of improved reservoir characterization model has shown that quality data leads to quality engineering and successful well completion optimization. Introduction In order to optimize the completions in the Jauf reservoir, a comprehensive data set was required to develop an improved petrophysical and mechanical properties model. Calibration of the models was done with core and production data where possible. In addition sanding was a problem associated with gas production in the Jauf. A new sanding model was built to assist in the completion strategy to reduce sanding potential/production.