Browsing by Subject "Relative Permeability"
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Item Inflow Performance Relationships (IPR) for Solution Gas Drive Reservoirs -- a Semi-Analytical Approach(2010-07-14) Nass, Maria A.This work provides a semi-analytical development of the pressure-mobility behavior of solution gas-drive reservoir systems producing below the bubble point pressure. Our primary result is the "characteristic" relation which relates normalized (or dimensionless) pressure and mobility functions. This formulation is proven with an exhaustive numerical simulation study consisting of over 900 different cases. We considered 9 different pressure-volume-temperature (PVT) sets, and 13 different relative permeability cases in the simulation study. We also utilized 7 different depletion scenarios. The secondary purpose of this work was to develop a correlation of the "characteristic parameter" as a function of rock and fluid properties evaluated at initial reservoir conditions such as: API density, GOR, formation volume factor, viscosity, reservoir pressure, reservoir temperature, oil saturation, relative permeability end points, corey exponents and oil mobility: We did successfully correlate the characteristic parameter as a function of these variables, which proves that we can uniquely represent the pressure-mobility path during depletion with specific reservoir and fluid property variables, taken as constant values for a particular case. The functional form of our correlation along with all relevant equations are shown on the body of this document.Item Numerical-based Study of Spent Acid Blockage Damage in Acidized Gas Wells(2013-12-04) Zhang, QiAqueous fluids introduced by different stimulation treatments cause water blockage in the near-wellbore region of wells. This water blockage acts the same as formation damage when the well is put back on production. One of the examples is when gas wells in carbonate reservoirs are acid-stimulated; the wormholes that propagate into the formations might be surrounded by a region of high aqueous fluid saturation created by the leakoff of spent acid. The spent-acid blockage damage could be severe, especially in lower permeability regions where capillary forces are relatively high. This research presents studies that investigate the spent-acid damage in wormhole region of acid-stimulated gas wells. We start the investigation with lab-scale coreflood experiments. With the experimental study, this work verifies the spent acid blockage phenomenon accompanying the acid stimulations. A model that simulates a gas flowback experiment is then developed to match with the results from the experiments. From this numerical simulation, we are able to obtain the information of the properties that cannot be measured directly from the experiments. We then extend the research to a field-scale study by approximating the wormhole as a long, slender half-ellipsoid centered in an ellipsoidal flow field. Models that can capture both the displacement and evaporation regimes of spent acid recovery process are developed. These models are solved numerically to predict the pressure behavior and spent acid distributions during the gas flowback process. With the numerical models, we study the effects of several key factors, such as pressure drop, pore-size distribution, and addition of additives on the efficiency of spent acid recoveries. The results show that the time needed to recovery the same amount of spent acid increases exponentially with decreasing pressure drop and absolute formation permeability. Besides, common additives routinely added to acid systems may aid, or hinder, spent acid recovery, depending primarily on their effects on rock wettability. With the studies performed on the model developed, we provide recommendations for minimizing spent acid damage to gas well productivity.