Job Description:
Within the framework of the "traditional approach", the actual parameters of the hydraulic fracturing crack (half-length, height, width, dimensionless conductivity) often differ significantly from those calculated at the design stage of fracturing due to the lack of accurate and comprehensive data on the mechanical properties of the formation. This increases the risk of the hydraulic fracturing crack breaking into a non-target formation.
To solve this problem, the results of borehole studies before and after hydraulic fracturing were analyzed. The influence of the following initial parameters on the crack geometry is estimated:
- well design;
- geomechanical properties of the medium (Poisson's ratio, Young's modulus, minimum horizontal stresses);
- download schedule;
- liquid and propane parameters;
- vertical and horizontal grid size;
- the step between calculations;
- the calculation area.
A retrospective analysis of the various tonnage hydraulic fracturing was performed, a 3D geomechanical model was built and calibrated.
A unified "geomechanical approach" to the creation of hydraulic fracturing designs and the definition of fracture geometry has been developed.
In the developed approach, core studies using destructive methods are carried out to calibrate elastic-strength properties. The stress profile is calibrated for the results of special studies (stress test, pickup test), injection tests and mini-fracturing, as well as drilling events.
Later, in the process of modeling fractures, the geomechanical model, namely the stress profile, is refined at the stage of mini fracturing. After clarifying the stress profile at this stage, the model is no longer subject to adjustments and is a tool ready for use in the design of hydraulic fracturing.
Result:
An integrated "geomechanical" approach made it possible to accurately predict the actual geometry of the crack even at the stage of developing a preliminary hydraulic fracturing design and avoid a breakthrough into the aquifer. The result was obtained at 10 wells, with confirmation of the fracture geometry by acoustic studies before and after hydraulic fracturing in vertical wells and microseismic monitoring in horizontal wells.
