تحليل انتشار صفحه‌يي ترك هيدروليكي در سنگ شكننده‌ي نفوذ ناپذير با درنظرگرفتن اثر نيروي اينرسي سيال

Hydraulic Fracture Propagation in Impermeable Elastic Rock with Large Toughness: Considering Fluid Inertia Parameter Effect

در اين پژوهش، يك روش تحليلي براي تعيين ميزان انتشار، بازشدگي و فشار سيال داخلي ترك در محيط كشسان به‌طور مثال براي سنگ هاي شكننده در حالت كرنش صفحه‌يي ارايه و سيال نيوتني و غيرقابل تراكم با چسبندگي ناچيز تحت نرخ ثابت در ترك تزريق شده است. در بيشتر مطالعات پيشين، اثر نيروي اينرسي در ميزان رشد و بازشدگي ترك ناديده گرفته‌ شده است. در اين نوشته، روش تحليلي اغتشاش هموتوپي براي درنظرگرفتن اين اثر پشنهاد شده است. در اين حالت مقادير سختي محيط نسبت به اينرسي و چسبندگي سيال بيشتر است. اين روش نه فقط كارايي درنظرگرفتن اثرات اينرسي، بلكه اثرات ديگري همچون سختي بالاي محيط كشسان و چسبندگي بالاي سيال را نيز دارد. براي تاييد و اعتبارسنجي، اين پژوهش با كارهاي انجام‌شده‌ي پيشين مقايسه شده است.

The problem of fluid-driven fractures in rock arises in various applications ranging from the hydraulic fracturing treatment used in the oil industry to stimulate oil production from underground reservoirs to the formation of intrusive dykes in the earth crust and magma transport in the lithosphere. Other applications include stimulation and heat extraction from geothermal reservoirs, induced caving in mining industry, soil grouting, and etc. In this paper, plane-strain hydraulic fracture propagation is investigated in an impermeable elastic rock under conditions of large toughness. The flow of incompressible fluid in the fracture is unidirectional and laminar. Fracture propagation is described in the framework of linear elastic fracture mechanics (LEFM). The fracture is fully fluid-filled at all times. The net pressure in the fracture, the crack opening, and the fracture half-length are obtained from the proposed analytical solution. On the other hand, the effect of inertia has not received adequate attention. The homotopy perturbation method is proposed for considering this effect on the otherwise toughness-dominated solution of a plane-strain hydraulic fracture. Also, it is equally applicable to either other fracture geometries and/or to evaluate viscosity effects on the solution. Generally, increased fluid inertia parameter, , induces an increase in fluid velocity, the net pressure in the fracture tip, and a decrease in the opening at the injection point. Since the net pressure in the zero-inertia solution has the minimum value at the injection point, the crack may have a tendency to develop a tear-drop shape for larger values of fluid inertia parameter, . The results imply that the tip velocity increases as increases. In design practice, this important aspect must be given proper attention. These results are compared with asymptotic solution results of Dmitry I. Garagash [Engineering Fracture Mechanics, 2006] and qualitatively, found to be in good agreement.