Water Injection Fracture Pressure and Fracture Propagation Investigating in Poorly Consolidated Sandstone

Abstract

Predictions of fracture initiation and propagation pressure are an essential prerequisite to determine reasonable injection pressure for poorly consolidated sandstone. Most models for hydraulic fracturing based on elasticity mechanics are not applicable for poorly consolidated rocks. The fluid-solid coupling model based on elastic theory of porous media for poorly consolidated sandstone is established to analyze fracturing modes and fracture initiation pressure by adopting the maximum tensile stress criterion and the Mohr-Coulomb criterion, and the calculation methods of water injection fracture pressure and water injection fracture propagation pressure are obtained in this paper. The study shows that fractures are mainly caused by shear failure and propagation direction is parallel to the maximum horizontal stress. The vertical and tangential effective stress are reduced with the increase of bottom-hole injection pressure. But the radial effective stress is just the opposite. So the transformation of the three principal effective stress values will occur with the increase of water injection pressure. The fractures paralleled to the radial direction of borehole are more easily propagate to formation interior when radial stress becomes intermediate principal stress. The work provides important guidance to determine the construction parameters micro-fracturing in water injection wells.

Research and Application of Optimization Technology for High-Efficiency Fracturing and Packing Parameters of Unconsolidated Sandstone

“…Zhang et al believed that high sand ratio, low displacement, and continuous slug sanding technology should be used to achieve end screenout [10]. Fan et al believed that high efficiency fracturing fluid induced fractures short and wide, and it can achieve the purpose of filling and sand control [11]. Li et al studied the critical sand production rate and sand production area of unconsolidated sandstone fracturing packing based on the fluid-solid coupling model [12].…”

New Mathematical Technique for Step Rate Test Analysis Aids Determination of Fracture Pressure and Overcomes the Uncertainty of Conventional Analysis

“…The SRT data often do not fit into a straight line and do not exhibit one clear change in slope, thus making it difficult to estimate the fracture pressure. It often becomes subjective and leads to more than one outcome when analyzed by different engineers, leading to erroneous results. Various past studies , indicated that interpretation of fracture pressures by conventional analysis from the SRT is often subjective.…”