<p> The average pore size in producing unconventional, liquids-rich reservoirs is estimated to be less than 100 nm. At this nano-pore scale, capillary and surface disjoining force interactions, such as van der Waals, structural, and adsorption, affect the phase behavior that is not considered to be significantly, different than in conventional reservoirs. In this dissertation, a comprehensive discussion of the thermodynamics required to model phase behavior of unconventional, liquids-rich reservoirs is presented. Three oil compositions from different unconventional reservoirs are used to generate results. </p><p> The impact of confinement manifests itself in the form of reduction of the liquid pressure at which the first gas bubble forms when compared to the bulk fluid measurements in PVT cells. It is shown that the suppression of the bubble-point pressure impacts the saturated portion of the liquid formation volume factor and extends the undersaturated portion of the curve. The equilibrium gas composition is different for each supersaturation level and the gas is composed of lighter components as the supersaturation, i.e., the bubble-point suppression, increases. The minimum radius of the pore that is required to form a specified size bubble is also investigated and the range of pore sizes required under different assumptions is reported. </p><p> The impact of this phase behavior deviation on the flow of confined fluids is investigated using a black-oil simulator, COZSim, which evaluates gas and oil fluid properties at corresponding phase pressures. The simulator was independently developed in a DOE project with the capability to incorporate the findings of this research. The results of the analysis show that there is a difference in gas production and gas saturation distribution in the reservoir with and without the confinement impact on the PVT properties. The produced GOR is lower when the confinement is considered due to the bubble-point suppression. These results indicate that the use of bulk fluid measurements in modeling and predicting the performances of nano-porous unconventional reservoirs may result in significant underestimation of the reservoir potential. </p>

Currently employed methods for treating produced water do not consistently meet regulatory limits on oil and grease discharge concentrations. Experiments with different produced waters using tubular, crossflow, ultrafiltration membranes demonstrated that oil and grease concentrations less than 14 mg/l (well below current regulatory limits) could be achieved. Ultrafiltration experiments on produced water and model oil emulsions demonstrate that virtually all colloidal organic materials are rejected by the membrane, while dissolved organic materials pass through it. The membrane rejects precipitated iron and suspended solids. Permeate flux behavior and the effectiveness of different cleaning procedures vary significantly among produced waters. Generalizations on permeate flux performance during ultrafiltration treatment of produced water do not appear to be warranted. Permeate flux ranged from 73 to 306 l/m$\sp2$-hr depending on the produced water source and the cleaning procedures. Pilot studies on specific produced waters may be necessary to insure this process' applicability.

<p> The limit of drilling ERD comes from the excessive friction between the drill string and borehole. This study investigates the potential of increasing the limit of horizontal displacement through optimization of drilling fluid and bottom hole assemblies. We conclude that lubricating bottom hole with water can significantly increase the maximum permissible WOB. This effect is more pronounced in drilling tight sands than shales with gas. Cooling the bottom hole with gas expansion after bit nozzles can greatly increase the maximum permissible WOB in drilling formations with geothermal temperatures above 200 &deg;C. Three mathematical methods have been developed for calculating the limit of horizontal displacement in extended drilling with gas. The Rigorous Method is recommended because it gives conservative result. Among several factors affecting the ERD with gas, friction coefficient and the weight of pipe in the horizontal section are the two controlling factors. Adequate weight of BHA in the curve section should be used to overcome the friction.</p>

<p> Analytical models were derived in this work to predict the Maximum Permissible Pressure (MaxPP) and Minimum Permissible Pressure (MinPP) in CO₂sequestration and other fluid injection wells. The outer radius of the cement sheath should be estimated on the basis of cement placement efficiency measured by the CBL. </p><p> The West Hastings Oil Field and Oyster Bayou Oil Field in Gulf of Mexico region were analyzed to identify the potential leakage of the current CO₂ injection wells using the analytical models. Potential problems for the current wells were identified. There are potential risks for the CO₂ injection wells with relatively smaller wellbore diameter and casing diameter.</p><p> 36 CO₂ injection wells of the West Hastings and Oyster Bayou fields were taken as learning wells to train the neural network model, which was tested by 21 wells in the fields. The results show that the neural network model could be used for predicting the potential likelihood of leakage for CO₂ injection wells, which could be an alternative and convenient way to assess the risk of leakage CO₂.</p><p> Sensitivity analysis was also performed considering cement mechanical properties, well structure and reservoir pressure. Results show that improving cement sheath mechanical properties (cement tensile strength, cement cohesive strength, internal friction angle) is not a very effective means of decreasing potential leakage of CO₂ during CO₂ EOR and carbon sequestration processes. The potential risk of leakage for CO₂ injection wells should be decreased by maximizing the outer radius of the cement sheath and improving the cement placement efficiency. For the current CO₂ EOR activities and carbon sequestration processes, the well head maximum water injection pressure could be increased as the reservoir pressure increases.</p>

<p>U.S. domestic shale-gas production is economic owing to the new completion practice of horizontal wells and multiple hydraulic fractures. The performance of these fractures is improved through the placement of proppant. The change in the stress can affect fracture conductivity considerably. The objective of this study is to experimentally determine the impact of rock stress and time on aperture and permeability of hydraulic fractures in shale gas reservoirs. </p><p> Seven experiments were conducted to measure pressure and time dependent closure and permeability of hydraulic fractures created in Barnett shale under different confining pressure. Result shows that pressure dependence of permeability of these fractures obeys Walsh&rsquo;s permeability models. Time dependence of permeability at high stresses reveals that proppant embedment occurred to the Barnett shale cores. </p>

The immiscible displacement of oil by water in a petroleum reservoir has been simulated in the laboratory using a consolidated porous medium constructed out of silica sand particles. Four distinct displacement flow modes were employed, namely horizontal, vertical upward, vertical downward, and transverse. Experiments were carried out by displacing the oil phase (heavy paraffin oil) by the aqueous phase (dyed glycerol solution) at different oil/water viscosity ratios, at different flow rates, and in the presence and absence of connate water (connate water is the name given to the very small amount of water that occurs naturally in petroleum reservoirs). The objective of this study was to investigate the effects of viscosity ratio, flow rate, and flow mode on the oil recovery efficiency. In the absence of connate water, a decrease in the oil recovery is observed when the oil/water viscosity ratio increases for all four flow modes but the displacement patterns are different for each flow mode. In the presence of connate water, the dependence of oil recovery on viscosity ratio is similar although in this case the displacement patterns are almost indistinguishable for the four different flow modes on account of coalescence of the connate water phase with the displacing aqueous phase. Without connate water, the highest recovery is obtained in the vertical upward mode where the buoyancy forces stabilize the displacement process. Conversely, in the vertical downward flow mode, the instability promoted by gravity leads to a low recovery. Comparison of the results obtained with and without connate water shows that connate water has a negative effect on the recovery and, moreover, that the synergistic effect between the viscosity ratio and the connate water reduces the oil recovery efficiency significantly.

When a higher-viscosity fluid is displaced by a lower-viscosity fluid in a porous medium, the displacing fluid tends to channel through the paths of lesser hydrodynamic resistance, thereby forming pronounced "fingers". The effects of buoyancy (gravity) forces on the stability of such displacement processes are of considerable importance in many practical situations, especially during the recovery of oil from underground reservoirs, or during the clean-up of subterranean toxic chemical spills, by means of aqueous fluid injection. The present work is confined to the former (i.e., oil recovery) situation. In this work, the effects of buoyancy forces on immiscible water/oil displacement processes and miscible oil/oil displacement processes were studied for linear flows occurring in a two-dimensional, consolidated, transparent porous medium aligned in either the vertical or horizontal plane. Experiments were performed using three different flow modes, namely horizontal, vertical-upwards and vertical-downwards. A wide range of injection flow rates were employed in order to elucidate the relative effects of buoyancy forces, viscous forces and capillary forces. For each displacement, the breakthrough condition was measured, and photographs of the evolving fingering patterns were taken. A mathematical analysis of the observed displacement phenomena produced an analytical relationship expressing the macroscopic water saturation profile as a function of dimensionless distance. The horizontal flow mode was employed as the reference condition for the prediction of the oil recovery efficiency in the two vertical flow modes, since buoyancy forces can be effectively neglected in horizontal flow. A reliable technique for measuring the saturation profile from the displacement photographs was developed in order to interpret the experimental data. Good agreement between the theoretical and experimental results was obtained, thereby permitting a reliable quantitative prediction of the effects of buoyancy forces on oil recovery during immiscible water/oil displacement processes. The extent to which the viscosity ratio, interfacial tension, and flow rate influenced the relative effects of the buoyancy forces will be discussed in relation to measured breakthrough times and oil recoveries. Also, the instability theory of the displacement will be discussed. It is evident from the results obtained that buoyancy forces are capable of exerting very significant effects on the stability of liquid-liquid displacement processes occurring in porous media, on the formation of fingers, and on the ultimate recovery efficiency during practical oil recovery processes involving aqueous fluid injection.

Swarms, of diabase dikes have been reported in all Provinces of the Precambrian Shield. One of these is the Buckingham swarm which extends into the region of the Gatineau Park. A fresh exposure of one of these dikes was sampled to study ids petrographic and chemical characteristics and any variations which might reflect the nature of its formation. The physical and chemical characteristics of the dike compare closely to those of Hawaiian tholeiitic basalts, and the sub-ophitic texture of this dike resembles that of typical diabase dikes. The dike appears to be a member of a swarm of diabase dikes of probable Ordovician age, and are located in the Grenville province of the Canadian Shield. Some variations in composition exist across the dike. (a) Mafic minerals decrease in quantity inward while plagioclase increases inward. (b) Grain size graphs plot in the shape of a bell curve, rather than parabolic. (c) The characteristic sub-ophitic texture is replaced by porphyritic texture in the contact samples. (d) An content of plagioclase decreases inward. (e) Silica content of bulk rocks decreases outward. (f) Rock compositions appear to have erratic variation in the zones near the contacts. The observed variation in texture and chemical composition within the study dike may be attributed to a combination of factors including; contamination, secondary alteration, and some form of differentiation.

Abstract not available.

<p> Steam stimulation is by far the most widely used tertiary oil recovery method. Heavy oil finds its most effective way of production in thermal recovery method. Also with technical effectiveness, steam stimulation brings in cost effectiveness. In-situ steam generation and injection is the most important enhancement to the conventional thermal steam injection technique. Blackbird&trade; Energy LLC, has developed and a new generation in-situ steam generator with a view to make an almost unproductive heavy oil reservoir in North East Texas to start producing. </p><p> In this research, a reservoir simulation study has been performed to history match of pure depletion as well as three months of thermal stimulation done on the reservoir. To mimic the reservoir conditions, Schlumberger Eclipse 300 compositional Simulator has been used. Overall this research performs an evaluation of the newly developed in-situ steam generator capabilities. </p><p> The various predictive runs have been made with changing key performance parameters such as location of steam generator and time of application of thermal energy. There has been reported a considerable increase in production of the heavy oil. As a result, in-situ steam injection has been proved to be an effective and environment friendly recovery technique and should be widely considered for replacing conventional steam generators.</p>