Role of Fracturing Fluid on the Breakdown Pressure of Tight Sandstone Rocks

Hydraulic fracturing is a well stimulation technique which increases the hydrocarbon production by inducing fractures in the rock formation. The induced fractures in the reservoir serve as highways for faster hydrocarbon movement. The process is carried out by injecting fracturing fluid which primarily contains gelling agent, crosslinker, bactericide, fluid loss additive, friction reducer, clay stabilizer, buffer, breaker and proppant mixed in a base fluid. Fracturing fluids are carefully selected for each rock formation. A Tight gas reservoir is commonly referred to as a low-permeability reservoir. Tight gas accounts for about 7 % of the world’s hydrocarbon resources which is about the same as the conventional gas (9 %). Enormous quantities of natural gas are present in these tight gas reservoirs. Unlocking these reservoirs is fairly challenging due to the amount of complexities associated with them. Geomechanics plays a key role in the extraction of hydrocarbon from tight gas reservoirs. Hydraulic fracturing is an integral part of geomechanics and is an essential operation to achieve economical production. The importance of fully understanding the fracturing process is critical in properly developing an efficient hydraulic fracturing plan. It’s a robust technique but there are still several uncertainties associated in its implementation. Therefore, this study aims to address some of the challenges for tight sandstone in the areas of geomechanics and hydraulic fracturing. The objective of this research is to develop an efficient experimental setup to determine the breakdown pressure of tight sandstone rocks. Effect of the type of fracturing fluid on breakdown pressure, effect of saturating fluid on the breakdown pressure and the geomechanical properties of tight sandstone rocks is studied in this research

Experimental Investigation and Modeling the Heat of Hydration in Mass Concrete Structures

The hydration of cement in mass concrete structures produces high temperature.The temperature in the core of the mass concrete structures is higher than the temperature in the surfaces that are closer to ambient air. This temperature gradient leads to the development of thermal stresses, which may cause cracking if thermal stresses exceed the tensile strength of concrete at early age. This research focuses on conducting an experimental program for 46 different mixes using iQdrum heat signature and heat box to obtain the heat of hydration and temperature rise. The mechanical properties of these concrete mixes such as tensile strength, compressive strength, and modulus of elasticity were also conducted. The effect of mineral admixtures, such as fly ash, ground granulated blast furnace (GGBFS) slag, and silica fume, on heat of hydration was investigated. The effect of steel and polypropylene fibers on the heat of hydration and on the cracking index of mass concrete at early age was studied. The temperature rise, the peak temperatures, and strains for different seven mock-up specimens and for actual structures such as pilescap, were monitored. The viscoelastic behavior of mass concrete at early age was simulated by using the finite element nonlinear approach The finite element model predicted the temperature rise in the mass concrete structures, and associated thermal stresses The finite element model has ability to indicate to whether the cracks will form or not. Based on experimental and numerical investigations, guidelines will be developed for mass concrete in Kingdom of Saudi Arabia (KSA). These guidelines will help in reducing the risk of cracking due to high temperature gradient between core of concrete and its surface