Abstract In this case study, fracture treatments in three tight-oil reservoirs in the giant Ordos basin of northern China were investigated using microseismic mapping and fracture modeling techniques to understand hydraulic fracture growth behavior and post-frac performance. Reservoirs of interests consist of stacked fluvial sand/shale deposits, and the target pay zones occur at depths between 1,820 and 2,186 meters. All wells in these tight reservoirs require fracture stimulation to improve productivity. This paper provides a brief summary
of reservoir characteristics, but focuses on microseismic mapping results and fracture modeling analysis. This paper demonstrates that integrated studies can help engineers understand fracture behavior.
Introduction This study involves three tight-oil reservoirs in the Ordos basin, which is located in north central China (as shown in Figure 1). The three reservoirs of interest are relatively close, and are located in an area of 40 by 40 kilometers. The net pay thickness for these reservoirs ranges from 8 to 15 meters. The reservoir quality varied with effective permeability ranging from 0.05 to 0.3 mD. The specific gravity of the crude oil is about 0.85 or an API gravity of 35 degrees. All oil wells in these tight reservoirs in the region require fracture stimulation
to achieve commercial production and to improve well productivity. Fracture stimulation is also very common for water injection wells to enhance injectivity. Figure 2 illustrates the surface environment in the Ordos basin. Canyons and deserts cover a major portion of the basin's surface area. A number of directional wells are thus often drilled from a single pad.