E. N. Sher

Propagation of closely spaced hydraulic fractures

The paper deals with the flat problem about stresses in the vicinity of two closely spaced hydraulic factures, as well as with the relationship of stress intensity factors, external and internal pressures of the fractures and their configurations. Based on the calculations, the authors have determined the influence zone of the existing fracture on the newly created crack. Besides, the new created fracture propagation paths in the stress field generated by the existing fracture are plotted, and the new created fracture curvature versus the values of the problem parameters is analyzed. Finally, the conditions for the new created fracture to be minimum curved have been determined.

Determination of conditions for compressed air-assisted removal of plastic soil in horizontal pipeline in drilling

Under discussion is plastic soil removal in horizontal rotating pipeline by air flow. It is experimentally proved possible to remove soil by batches generated during rotation of the pipeline. The found relationship between soil conveying in the pipeline, the pipeline diameter and air forward pressure is made the basis for determination of the parameters of the main transporting line in a drilling installation.

Crack Development under Pulse Hydraulic Fracturing of Rocks

The calculation scheme is developed for describing the hydraulic fracturing of rocks by explosion of charge in well. The investigation is conducted within the quasi-static approach to the analysis of crack propagation in the productive stratum.

Calculation of Fluid Flow in the Oil Well under the Action of Powder Gas Generator

A numerical algorithm is developed, and the parameters of fluid flow in the oil well under the action of powder charge are calculated. For different combustion conditions, the dependence of gas pressure on the time and the maximum amplitude of fluid rise are found. The value is obtained for decreasing the pressure in the well relative to the hydrostatic pressure in the stratum; the hydrostatic pressure arises in cooling down the gases to the ambient temperature.

Dynamics of Microfailures in Elastic Zone during Explosion of Spherical Charge in Rock

A calculated model is developed for explosion of spherical charge in rock; it takes into account accumulation of damages in the elastic zone under the action of blast wave. The condition, under which the density of generated microcracks reaches the critical value, is used as failure criterion. The microcrack growth rate is determined by exponential function of equivalent stress.

Determination of hydrofracture geometry in a production reservoir

The article describes numerical modeling of growth of five successive hydraulic fractures in the directions transverse to the well, in plane and axisymmetric elastic problems, under assumption of perfect breakdown fluid. The zone of influence of the existing created fractures on the newly initiating hydrofractures is defined, and the pressure for a new fracture to grow is evaluated. Parameters governing distortion of fractures are determined. The calculations in the framework of the plane and axisymmetric problems are compared.

Statistical Modeling of Rock Failure under Biaxial Compression. Part I: Shear Crack Interaction

The shapes and dimensions are determined for the regions of tensile stress concentration under the interaction of two shear cracks in the biaxial compression field. The statistical model for shear microcrack accumulation and main rupture formation is developed. The influence exerted by microcrack orientation and ratio of principal stresses on the direction of main rupture propagation is studied.

Calculation of Oil Reservoir Productivity with Horizontal Crack Formed by Hydraulic Fracturing

The approximate one-dimensional solution is proposed for the problem on filtration in the reservoir-crack system.

3D modeling of fracture growth in solid under the penetration of rigid wedge

The authors have undertaken experimental and theoretical modeling of fracture growth under the penetration of rigid wedge in brittle rock. The test specimens were made of organic glass to facilitate measurement of size and shape of a fracture. The wedge loading was executed quasi-statically on a testing machine and dynamically by a drop wedge. The scheme developed in the framework of the theory of elasticity for the theoretical description of the fracture growth process accounts for the finite size of the wedge cutting point and the influence of free surface. The theoretical and experimental shapes of fractures are compared.

Modeling propagation of multiple axially symmetrical hydrofractures

The article discusses growth of two successive axially symmetrical hydraulic fractures in line with a well. Shapes of the surfaces of the second hydrofracture that propagates in the stress field initiated by the first hydrofracture are modeled, and the pressure for the second fracture to grow is calculated. The authors assess impact area of the first hydrofracture, analyze options of the second hydrofracture curving and derive formula of the second hydrofracture curving.