Surfactant formulations consisting of surfactant, alkali, polymer, and electrolyte have been developed using well defined screening processes established through experimentation in labs around the world. Due to recent advances in chemical enhanced oil recovery, surfactants can be used to extend the life of mature reservoirs with increasingly diverse conditions. High temperatures, complex geochemistry, or high clay content can provide significant challenges when developing formulations for chemical flooding. Through careful selection and screening of surfactants and chemicals, oil recovery of greater than 90% can be achieved in laboratory corefloods despite these difficulties. The objective of this research was to determine the ideal surfactant formulation using a sulfate surfactant for a reservoir with high clay content at 85 ºC. Advances in our laboratory have shown sulfate surfactants to be stable under specific conditions at elevated temperature. In addition, new methods of synthesizing surfactants have yielded a vast array of structures and iterations of novel surfactants to test for EOR applicability. Experiments contained within include surfactant screening both with and without the presence of crude oil and evaluation of polymer and microemulsion viscosity. From these results, a series of corefloods were performed in Berea and reservoir corefloods that yielded oil recovery of 90% and above with low surfactant retention. / text

Surfactant-polymer (SP) and alkali-surfactant-polymer (ASP) flooding has gained little traction among different tertiary recovery strategies such as thermal and miscible gas flooding; however, many mature onshore reservoirs could be potential candidates. More than four decades of research has detailed technical challenges and successes through laboratory experimentation, chemical flood simulation, and some pilot projects, which have provided technical screening procedures to efficiently filter unfeasible projects. Therefore, technical understanding seems sufficient to advance projects through early development stages; however, a project value identification and realization process ultimately dictates project implementation in the oil and gas industry, with technical feasibility merely supporting overall valuation and project feasibility. A quick early screening methodology integrating important project valuation criteria can efficiently assess large numbers of projects. The relatively few studies detailing chemical flooding valuation from just an economic standpoint reflects the need for an integrated process-oriented framework for quick early screening valuation of chemical flooding opportunities. This study develops an integrated process-oriented framework for early screening and valuation, with an overall objective to quickly filter unfeasible projects based on valuation criteria, rather than technical feasibility alone. A reservoir-to-market model was developed, integrating information from laboratory experiments (phase behavior, core flood), field analogues (well performance and layout), facilities, rigs, costs, scheduling, and economics. Recently published ASP flood data of the central Xing2 area in Daqing, China was used for model inputs. A reservoir-to-market benchmark model for a typical mature onshore field was successfully built and tested, and could value projects using standard economic metrics (net present value, internal rate of return, value investment ratio, unit technical cost, and payback period). Model simplification was achieved through global sensitivity analysis. Using a mean-reversion oil price model, the oil price accounted for 98% of the total sensitivity. . Model efficiency was achieved through discretization of input parameter uncertainties, which sped the screening process. Decision-making between model alternatives given information and different states of nature was performed through decision-tree techniques based on overall project valuation. Overall, this study was novel and provided benefit as a robust, integrated process-oriented framework for chemical EOR project screening, valuation, and decision-making. / text