Conformance improvement is the key to success in most enhanced oil recovery (EOR) processes including CO2 flooding and steamflooding. In spite of technical and economic limitations, foam has been used as dispersions of microgas bubbles in the reservoir to enhance mobility. Steam-foam has numerous applications in the industry, including heavy oil reservoirs, which are a significant part of the future energy supply. Steam-foam applications have been used to prevent steam channeling and steam override, thus improving overall sweep efficiency, in both continuous steam and cyclic steam injection processes. The objective of this study is to investigate the key components of this complex process, where relatively high temperatures are recorded, in order to have a robust understanding of chemistry and the thermal stability of surfactants. The efficiency and therefore economics of the steam-foam process are strongly reliant on surfactant adsorption and retention. This requires a good understanding of the process for effective sizing of the foam injected. In this study, a commercial reservoir simulator is used where surfactant transport is modeled with surfactant availability and is determined by a combination of surfactant adsorption, surfactant thermal decomposition, and oil partitioning due to temperature. The degree of mobility decrease is interpolated as a result of factors that contain aqueous surfactant kind and concentration, the presence of an oil phase, and the capillary number. An empirical foam modeling method is employed with foam mobility decrease treated by means of modified gas relative permeability curves. The simulation results outline the sensitivity of these parameters and controlling agents, providing a better understanding of the influence of surfactant adsorption and thus, a number of chemicals to be used in an efficient manner. Optimum values for decision parameters that we have control on have been determined by coupling a commercial optimization software with the reservoir simulator. Uncertainty parameters such as surfactant adsorption have been analyzed in terms of significance on the recovery process. Even though steamflooding is thoroughly studied in the literature, there is no recent in-depth study that not only investigates the decision parameters but also uncertainty variables via a robust coupling of a reservoir simulator and an optimization/uncertainty software that model use of foam in steamflooding. This study aims to fill this gap by outlining the optimization workflow, the comparison of parameters with tornado charts and providing useful information for the industry.

Voidage replacement is a key element in displacement processes, not only for keeping the reservoir pressure at its initial level but also in mitigating surface subsidence in certain fields. Despite its simple definition, it is a complicated process in reservoir management because of uncertainities involved and lack of all required measurements due to economical or technical restrictions. Thus, every single decision parameter and their relative significance in voidage replacement process is important for robust reservoir management. In general, voidage replacement is achieved where injection is based on production. This study investigates the case of triggers where the production rate at the bottom hole conditions is predicated on the bottom hole flowing conditions or reservoir gas injection rate. A full-physics commercial reservoir simulator is coupled with robust optimization software, where a miscible flood operation is modeled with a group bottom hole flowing target coupled with voidage replacement gas and water injection targets. The simulation results of this realistic case is presented in a way to show the relative significance of each operational parameter, which is outlined with tornado charts to serve as a guide in decision making in efficient reservoir management where voidage replacement is a crucial component. It is observed that triggers help to better manage voidage replacement, especially in large reservoirs where reservoir surveillance is a challenge due to number of wells and patterns. The results can be scaled up to different size of reservoirs and patterns with similar recovery processes. This study scrutinizes the feasibility of a reversal of the typical scenario where injection is based on production. Thus, it serves as a useful and realistic example for efficient reservoir management through optimization of voidage replacement through triggers for production rate.

Multiple analysis has indicated that over 50% of the oil production in the next 20-25 years is going to be produced through enhanced recovery procedures including polymer flooding. The heuristics for polymer flooding says that it is feasible to apply polymer flooding in reservoirs having oil viscosities in the range of 10 to 150 mPa.s. The main factor limiting this heuristic limit for polymer floods is that the injected water viscosity required for higher mobility ratio leads to pumping inefficiencies and low polymer injectivity rates. In this paper, we suggest a supramolecule based on the complexation of a long-chain amino-amide and maleic acid which can adjust its viscosity values reversibly to overcome the heuristic problem related to polymer floods. The concept is fundamentally based on the fact the supramolecule system which is injected in the reservoir will initially be maintained at a low viscosity and on application of external pH stimuli will increase in viscosity values prior to contact with oil. Our laboratory studies indicate that such a system is also tolerant to high temperatures and salinities Popular polymer systems used floe EOR purposes on experiencing extreme shear stresses and temperature break-up and degrade, however the supramolecule system dissemble and reassemble making the supramolecular system "healable" in a manner. The supramolecular systems can also adapt to confining environments, for example, on flow through narrow channels, the supramolecules undergo molecular scission. The supramolecules proposed could be used for viscous oil in thin oil sand zones, permafrost and other environmentally constraining systems. This paper primarily focusses, on the development and properties of a novel supramolecular system which has adjustable viscosities and interfacial properties and can be resistant to high temperatures and salinities. This Supramolecular system can significantly improve the feasibility and cost-effectiveness of a polymer flood process and can be utilized universally.

Diatomites are high-porosity, low-permeability reservoirs with elastoplastic properties and high geo-mechanical responsiveness. They have a great potential for oil recovery despite these drawbacks. Withdrawal of fluids from the reservoir rock leads to subsidence causing compaction and shear stresses. This disturbed stress distribution results in well failures that causes loss of millions of dollars. Successful maintenance of pressure support through optimum injection/production is key to preventing subsidence to mitigate the risk of well failure and achieve better sweep efficiency for recovery. There have been different approaches to tackle subsidence and well failures in diatomites, including the use of ‘backpressure method’, coupled with a neural network to optimize injection-production to ‘balance’ the rock in terms of stress-distribution and thus decrease well failure due to shearing. However, using such methods may mask other problems the well is experiencing including several mechanical issues that influence production. Another existing approach, satellite-imaging (InSAR) cannot be used to take real-time actions that is crucial in diatomites. Surface tiltmeter data is collected to undertsand the relationship between injection/production and resulting surface deformation, which also provides information about well-to-well connectivity. A neural network-based approach is followed to determine the nonlinear relationship between surface subsidence/dilation and injection-production. This is then used to build an objective function that works to minimize the differences between well-to-well subsidence/dilation measured by the tiltmeters, by adjusting injection-production for the wells. In this paper, a method that harnesses real-time surface tiltmeter data to adjust injection-production distribution in diatomites to decrease well failures is used beyond the existing applications of surface tiltmeter, for instance, in the areas of detection of early steam breach to surface in steam operations and fracture orientation. This method also provides real-time data for robust reservoir management of such reservoirs where satellite imaging is not effective.

Current analyses indicate that 50% of oil produced in USA and the world will be through EOR technologies in the next 20-25 years, and heuristics suggest that polymer flooding should be applied in reservoirs with oil viscosities between 10 and 150 mPa.s. The key factor limiting the recommended range is that for oil viscosities greater than 150 mPa.s, where injected water viscosity values required for a favorable mobility ratio give rise to prohibitively low values of polymer injectivity and pumping efficiencies. Herein, we propose that a novel type of supramolecular system based on the complexation of long chain amino amides and maleic acid with reversibly adjustable viscosities can enable us to overcome the injectivity limitation. The concept is that viscosity of the injected supramolecular system will be maintained initially at low values for easy injection and pumping, and then increased by means of an external pH stimulus just before or upon contacting oil. Our promising lab-scale preliminary studies have indicated that such supramolecular systems possess not only reversible pH-responsive properties, but are also very tolerant to high salinities and temperatures. While polymers degrade and break up upon experiencing sudden extreme shear stresses and temperatures, supramolecular solutions merely disassemble and re-assemble. Therefore, supramolecular solutions can be considered as healable polymer solutions in a way. Supramolecular solutions can adapt to the confining environment. For instance, when a high molecular weight polymer macromolecule is forced to flow into narrow channels and pores, molecular scission processes may take place. Supramolecular solutions can have a significant impact in the cases where thermal methods cannot be used for some viscous oils due to thin zones, permafrost conditions and environmental constraints. This project is primarily aimed at developing novel supramolecular assemblies with adjustable viscosity and interfacial properties that have robust tolerance against high temperatures and salinities. Such supramolecular assemblies will be used to significantly improve the feasibility and cost-effectiveness of displacement fluids used in EOR. Overall, there is a significant potential for application of supramolecular solutions in the US and throughout the world.