Showing papers by "Maurice B. Dusseault published in 2011"

Geomechanical challenges in petroleum reservoir exploitation

Abstract: Petroleum geomechanics deals mainly with coupled problems requiring simultaneous consideration of changes in temperature, pressure, stress, and chemical potential (THMC). Major current challenges in this domain include: accurate delineation of in situ physical properties and conditions (T, [σ], p), especially for naturally fractured reservoirs; wellbore wall stability predictions in swelling and fractured shale strata; modeling and monitoring of multiple-stage hydraulic fracturing used for development of resources in low-permeability rocks; controlling or exploiting sand ingress into producing wellbores; predicting subsidence accurately enough so that rational design decisions can be made; mitigating or reducing the incidence of casing shear arising from subsidence or thermal reservoir stimulation; understanding and analyzing thermal production processes in viscous oil reservoirs; monitoring of deformations in and around reservoirs being subjected to complex processes; and, a newer development, using the deep sedimentary basin environment for the permanent and secure disposal of fluid and granular wastes. Given the importance of fossil fuel energy in our industrial societies (>80% of all primary energy provision), the rewards for better engineering are significant.

Empirical Modeling of Gravity Drainage in Fractured Porous Media

Abstract: Gravity drainage is considered to be the main mechanism in primary oil production from naturally fractured reservoirs, but mathematical models to adequately predict the oil recovery and flux rate b...

Multi-stage fracture injection process for enhanced resource production from shales

Abstract: The invention relates to a method of generating a network of fractures in a rock formation for extraction of hydrocarbon or other resource from the formation. The method includes the steps of i) enhancing a network of natural fractures and incipient fractures within the formation by injecting a non-slurry aqueous solution into the well under conditions suitable for promoting dilation, shearing and/or hydraulic communication of the natural fractures, and subsequently ii) inducing a large-fracture network that is in hydraulic communication with the enhanced natural fracture network by injecting a plurality of slurries comprising a carrying fluid and sequentially larger-grained granular proppants into said well in a series of injection episodes.

Experiments on Methane Displacement by Carbon Dioxide in Large Coal Specimens

Abstract: Carbon dioxide (CO2) is considered to be the most important greenhouse gas in terms of overall effect. CO2 geological storage in coal beds is of academic and industrial interest because of economic synergies between greenhouse gas sequestration and coal bed methane (CH4) recovery by displacement/adsorption. Previously, most work focused on either theoretical analyses and mathematical simulations or gas adsorption–desorption experiments using coal particles of millimeter size or smaller. Those studies provided basic understanding of CH4 recovery by CO2 displacement in coal fragments, but more relevant and realistic investigations are still rare. To study the processes more realistically, we conducted experimental CH4 displacement by CO2 and CO2 sequestration with intact 100 × 100 × 200 mm coal specimens. The coal specimen permeability was measured first, and results show that the permeability of the specimen is different for CH4 and CO2; the CO2 permeability was found to be at least two orders of magnitude greater than that for CH4. Simultaneously, a negative exponential relationship between the permeability and the applied mean stress on the specimen was found. Under the experimental stress conditions, 17.5–28.0 volumes CO2 can be stored in one volume of coal, and the displacement ratio CO2–CH4 is as much as 7.0–13.9. The process of injection, adsorption and desorption, displacement, and output of gases proceeds smoothly under an applied constant pressure differential, and the CH4 content in the output gas amounted to 20–50% at early stages, persisting to 10–16% during the last stage of the experiments. Production rate and CH4 fraction are governed by complex factors including initial CH4 content, the pore and fissure fabric of the coal, the changes in this fabric as the result of differential adsorption of CO2, the applied stress, and so on. During CO2 injection and CH4 displacement, the coal can swell from effects of gas adsorption and desorption, leading to changes in the microstructure of the coal itself. Artificial stimulation (e.g. hydraulic fracturing) to improve coalbed transport properties for either CO2 sequestration or enhanced coal bed methane recovery will be necessary. The interactions of large-scale induced fractures with the fabric at the scale of observable fissures and fractures in the laboratory specimens, as well as to the pore scale processes associated with adsorption and desorption, remain of profound interest and a great challenge.