The development of an optimal hydraulic fracturing design, especially in regions with a complex tectonic regime, under conditions of high temperatures and abnormal high pore pressure, in horizontal wells, requires an integrated approach based on geomechanical modeling.
The Mechanical Earth Model (MEM) provides input information for calculating the parameters of the hydraulic fracture. It also uses data on the design of the well, tubing through which fluid is injected, perforation intervals, lithology and petrophysical parameters of the formation - porosity, permeability, fluid saturation.
The calibrated parameters of the MEM model are calculated taking into account various factors: redistribution of stresses in the perforation zone, tectonic regime, cooling of the near-wellbore zone due to circulation for ultra-deep wells, etc. Thus, the use of the results of geomechanical modeling increases the accuracy of determining the parameters of the hydraulic fracture and injection.
An integrated approach to hydraulic fracturing optimization makes it possible to determine the fracture geometry and fracture pressure with high accuracy. In the process of optimizing hydraulic fracturing modes, many scenarios of fracture development are considered depending on the injection parameters and stimulation intervals. This makes it possible to select the optimal fluid injection schedule with proppant. This approach avoids the risk of breakthrough into non-target intervals, reduces friction losses, and produces fractures with a high proppant concentration.
Multi-stage hydraulic fracturing
In horizontal wells and wells with poorly permeable formations, multi-stage hydraulic fracturing technology is often used. The difference from the one-stage one is that MSHF is carried out cycle after cycle, at different depths along the wellbore (MD).
For multi-stage hydraulic fracturing, it is possible to determine the optimal distance between stages or wells. To do this, when calculating the stress-strain state of the medium, the influence of hydraulic fractures on each other is considered. Also, the direction of the horizontal well and the position of the wellbore in the reservoir can affect the success of hydraulic fracturing and increase production.
Most accurately, such calculations can be made based on 3D geomechanical modeling.
As a result of complex hydraulic fracturing modeling, it is possible to determine:
- Direction and geometry of fracture propagation
- Dependence of fracture geometry on initiation interval.
- Vertical barriers for fracture propagation
- Optimum injection volume and pressure
- Shear and fracture initiation pressure for open hole and perforations, depending on phasing.
- Influence of Open Hole and Perforation Failures on Premature Proppant Stops.
- Optimal distances between multi-stage hydraulic fracturing for horizontal wells
- The optimal direction of the well, the location of the wellbore relative to the boundaries of the reservoir and the main barriers, the distance between the wells.
- Fracture closure and fracture stress for proppant selection
Reports and publications:
Based on the results of one of the works of our specialists in the design of hydraulic fracturing in an ultra-deep well with a complex tectonic regime under conditions of high temperatures and pressures, a report was prepared at the SPE oil and gas conference in 2018 and an article was published (Document ID SPE-191723-18RPTC-RU).
