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Abstract The aim of this paper is to investigate the fracture aperture behavior when secondary cracks occur on the main fracture surface. This phenomenon has not been analyzed in the literature. The investigation shows that the aperture profile of a hydraulic fracture with secondary cracks is no longer a smooth elliptical shape as it used to be when there is no secondary crack, but an irregular shape containing discontinuities (also called jumps). The jump keeps on growing with time when the secondary crack propagates into the formation. The investigation also reveals that the aperture profile of the hydraulic fracture with secondary cracks can be larger or smaller than the one without secondary cracks depending primarily on following factors: permeable (leakoff) or non-permeable (no leakoff) media, locations of secondary cracks and pressurization on the secondary crack surfaces. With the existence of secondary cracks, the location of the maximum fracture aperture is no longer at the centre of the fracture. The study has led to two main conclusions: (i) The effects of secondary cracks on the hydraulic fracture geometry emphasize the important role of geomechanics when simulating a hydraulic fracturing problem. Without considering geomechanics, the jumps in the aperture profile can never been seen; (ii) Abnormal changes in the profile of the main hydraulic fracture with secondary cracks can strongly influence the fracturing stimulation process.
- North America > Canada (0.28)
- South America > Brazil (0.28)
ABSTRACT This work presents theory for modeling of fracture propagation within reservoir simulator, history matching of field injection pressure using uncoupled and fully coupled geomechanical injection models, and sensitivity study of various parameters such as permeability enhancement/reduction functions, limiting length of fracture propagation, stress factor, and Biot's constant. Two wells completed in tight gas sands in Western Canadian sedimentary basin were studied. The wells were fractured with different techniques (i.e., X-link gelled water fracs (WellA) and un-gelled slick water fracs (Well B)) and were both successfully matched with coupled geomechanical mode
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.72)
- North America > Canada > Saskatchewan > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Northwest Territories > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > Canada > Manitoba > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- (2 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation > History matching (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
ABSTRACT With almost two hundred coal burning power plants in Ohio River valley, this region is considered important for evaluation of CO2 storage potential. In a CO2 storage project, the temperature of the injected CO2 is usually considerably lower than the formation temperature. The heat transfer between the injected fluid and rock has to be investigated in order to test the viability of the target formation to act as an effective storage unit and to optimize the storage process. In our previous work we have introduced the controversial idea of injecting CO2 for storage at fracturing conditions in order to improve injectivity and economics. Here we examine the thermal aspects of such process in a setting typical for Ohio River Valley target formation. A coupled flow, geomechanical and heat transfer model for the potential injection zone and surrounding formations has been developed. All the modeling focuses on a single well performance and considers induced fracturing for both isothermal and thermal injection conditions. The induced thermal effects of CO2 injection on stresses, and fracture pressure, and propagation are investigated. Possibility of shear failure in the caprock resulting from heat transfer between reservoir and the overburden layers is also examined. In the thermal case, the total minimum stress at the wellbore decreases with time and falls below the injection pressure quite early during injection. Therefore, fracturing occurs at considerably lower pressure, when thermal effects are present. The coupled thermal and dynamic fracture model shows that these effects could increase the speed of fracture propagation in the storage layer depending on the injection rate. These phenomena are dependent primarily on the difference between the injection and reservoir temperature.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.47)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/9 > Sleipner Field > Draupne Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/8 > Sleipner Field > Draupne Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > South Viking Graben > PL 046 > Block 15/6 > Sleipner Field > Draupne Formation (0.99)