Numerical modeling of thermal fracture development in unconventional reservoirs

Rapid depletion of hydrocarbons in conventional reservoirs and the availability of abundant oil and gas resources in unconventional forms demand new technology to economically produce these energy resources. From exploration to consumption of hydrocarbons, a great number of complex physical, chemical, mechanical, electrical, and thermal phenomena occurs in reservoir from reservoir rock to surface facilities. In addition to good rock samples and cores which could represent the reservoir rock for laboratory experiments, numerical tools should always be used to provide predictive capability of reservoir rock and fluid behavior. A great number of numerical methods have been developed and used over the past decades for rock mechanics problems. In this research the main focus is on thermal fracturing, heat transfer in rock, flow in porous media and stress-deformation analysis. We use three numerical methods for thermal fracturing of reservoir rock and investigate their capabilities in providing a solution for fracture propagation in rock. We finally propose the best numerical method among the ones we used in this work. We finally show two applications of thermal rock fracturing for improvement of hydrocarbon recovery in tight formations.Petroleum and Geosystems Engineerin

Evaluation of surfactant flooding using interwell tracer analysis

Surfactant flooding is an important enhanced oil recovery (EOR) method, especially in carbonate oil reservoirs where water flooding may not have an effect on oil recovery as much as for sandstone reservoirs. This is because of the initial wettability of most carbonate reservoirs that is mixed- or oil-wet. Since surfactant flooding has a great impact on both fluid–fluid and rock–fluid interactions, it can be an efficient EOR method for these kinds of reservoirs. Surfactants affect fluid–fluid interactions by reducing interfacial tension (IFT) between water and oil phases and rock–fluid interactions by wettability alteration. The objective of this paper is the evaluation of these two surfactant mechanisms in non-fractured carbonate reservoirs using UTCHEM, the University of Texas chemical compositional simulator. In this paper, first, the laboratory data of two surfactant spontaneous imbibition tests for carbonate cores are successfully matched with modeled data to evaluate the mechanisms of surfactant flooding. Second, the field-scale surfactant flooding is simulated using the experimental data from spontaneous imbibition tests. Several cases are modeled in order to study the effect of surfactant flooding in terms of decreasing IFT and wettability alteration. Since the formation brine salinity in most reservoirs is more than the optimum salinity of surfactant phase behavior, the benefit of combining surfactant and low-salinity water is also investigated. Finally, tracer test simulation is performed to estimate the average oil saturation within the swept pore volume at the end of each recovery mode

Method of improving hydraulic fracturing by decreasing formation temperature

A method for producing fractures in a formation to release hydrocarbons (such as a hydrocarbon gas or liquid) from the formation is disclosed. The method comprises reducing the in-situ temperature at a location in a formation having a first temperature by contacting the location with a first fluid and contacting the location with a fracturing fluid to produce fractures in the formation while the location is at a second temperature below the first temperature to release hydrocarbons from the formation. The method can include using an endothermic process to reduce the temperature at the location in the formation.Board of Regents, University of Texas Syste