Manouchehr, HaghighiFei, Yang2019-05-302019-05-302017http://hdl.handle.net/2440/119242Hydraulic fracturing is a well-known stimulation technique for creating fractures in a subsurface formation to achieve profitable production rates in a wellbore. The process involves the injection of a high-pressure fracturing fluid to induce fractures around the wellbore in a target interval enhancing oil and gas production in damaged wells or low permeability reservoirs. The pressure of injecting fracturing fluid should be high enough to overcome the subsurface in situ stresses and tensile strength of a fluid saturated porous rock, forming a tensile crack or fracture. Sand or other hard solid particles, referred to as proppant, is added in later stages of pumping. The fracturing fluid is required to have sufficient viscosity to suspend and carry the proppant deep into the created fracture system to keep the fractures open after hydraulic fracturing operation and during flowback and hydrocarbon production. Slick water or cross-linked gel is currently used as fracturing fluid in almost all hydraulic fracturing operations. Foam as an alternative fracturing fluid is attracting attention because their liquid content (water) is small, reducing the water usage and reducing damage potential to water-sensitive formations. Foam as a fracturing fluid should remain stable to be able to carry a large amount of proppant. Gas-in-water foams is generally not stable in the presence of a surfactant, particularly in high temperatures reservoirs. Previously, guar gel and synthetic polymers were used as foam stabiliser. However, the damage to the formation increases because of the presence of gelling residue. Thus, stable foam with low formation damage is a key factor for the extensive use of foam as a fracturing fluid. The principal goal of this study is to develop non-damaging and stable foam, which can transport proppant effectively. The secondary objective is to evaluate the performance and the stability of the developed foam using proppant placement efficiency (large uniform proppant distribution) and water usage efficiency (less water consumption to generate comparable or better productivity). In this study, a non-damaging and stable foam is developed using silica nanoparticles and a living polymer made of worm-like surfactant micelles. The experimental results show that foam stability increases two to three times in the presence of 0.8 wt% silica nanoparticles under 90 ℃. The enhancement of foam lifetime by nanoparticle application allows better proppant suspension, which maintains post-fracture conductivity and minimise productivity loss. The simulation results show that foam stability is directly dependent on proppant placement and fracture conductivity distribution. When foam fracturing fluids experience long closure time, foam breakage leads to proppant settling and accumulation at the bottom of the formation; which causes reduction of the propped dimension. Both a high pumping rate and high foam quality provide a large initial propped area; however, foam stability is still the major factor that controls the final propped area, and the resulting productivity. Those results are critical findings for developing a guideline for an optimized application of nano-stabilised foams in unconventional reservoirs.enHydraulic fracturingFoam stabilityProppant placementRheologyThesis