The 1984 Natl. Petroleum Council Study on EOR: Chemical Processes

Abstract

Summary The chemical flooding portion of the 1984 Natl. Petroleum Council (NPC) study of enhanced oil recovery potential for the U.S. is reviewed. Recovery from chemical methods was estimated at around 2.4 billion bbl [381×106 m3] using implemented technology and 10.9 billion bbl [1732×106 m3] for advanced technology for an oil price of $30/bbl [$188/m3]. Introduction The 1984 NPC Study on Enhanced Oil Recovery1 evaluated the potential of three major EOR methods: thermal, miscible, and chemical flooding. The study used an extensive reservoir data base that represented about 70% of the total original oil in place (OOIP) in known U.S. reservoirs. The chemical flooding portion of the study considered three processes---polymer, surfactant, and alkaline flooding. Screening criteria developed on the basis of chemical EOR projects conducted to date allowed selection of reservoirs amenable to each process. The incremental oil recovery obtainable from these reservoirs was estimated with simplified predictive models for each process. Each model included an economic subroutine that accounted for costs associated with the EOR process and calculated a discounted cash flow rate of return (EOR). A minimum EOR was used to screen projects according to the likelihood of favorable economics. Recovery potentials at various minimum rates of return were estimated for oil prices ranging from $20 to $50/bbl [$125 to $3l4/m3]. The study considered two technology cases. The implemented technology case represents process efficiencies already demonstrated in field tests or commercial applications. The advanced technology case assumed that process improvements currently at the laboratory stage will evolve successfully into field application. The results of the study indicate that total EOR potential for chemical flooding ranges from 1 billion bbl at $20/bbl [160×106 m3 at $l25/m3] oil to 4.1 billion bbl at $50/bbl [650×106 m3 at $3l4/m3] oil for implemented technology. Recovery could reach 13.5 billion bbl at the $50/bbl [214×106 m3 at $3l4/m3] oil price for the advanced-technology case. In both cases, most of this projected recovery is expected to come from surfactant flooding. Purpose and Methodology The purpose of the Chemical Task Group of the NPC EOR committee was to estimate the potential incremental oil production from known U.S. fields with polymer, surfactant, and alkaline flooding. Estimates were also made of the rates at which this oil might he produced during the next 30 years.1 The study methodology involved the following steps:identifying reservoirs for each process with reservoir and process screening criteria,predicting oil recovery and economics for each project, andcombining results from individual reservoirs to give the overall reeovery and overall producing rate for each process. The starting point for Step 1 was use of the reservoir data base developed specifically for the NPC EOR study. The fields included in this data base represented about 70% of the OOIP in known U.S. fields. Screening criteria were applied to this data base to determine reservoirs suitable for each chemical process. Simplified predictive models were used in Step 2 to estimate the amount of incremental oil obtainable from each suitable reservoir/process combination. Discounted cash flow EOR was calculated for each project. To provide an economic screen, a minimum acceptable EOR was set. Step 3 considered chemical EOR in competition with other EOR methods. If more than one process proved economical for a given field, preference was given to the process that recovered the most oil. At this stage, it was necessary to determine an initiation date for each EOR project. Projects that appeared to be the most profitable were started first. Other factors affected project timing, including the amount of surfactant available. Once project start dates were set, composite production curves were generated by summation of production histories for individual projects. Technology Cases The study considered two technology cases. The implemented-technology case represents ranges of applicability and process efficiencies already demonstrated in technically successful field projects. The advanced-technology case assumes that current research will improve process efficiency and extend chemical processes into reservoirs where they are currently not applicable. For timing purposes, it was assumed that advanced technology would become available in 1995. Related papers: SPE 13239, SPE 13240, SPE 13241 Related discussions and replies:SPE 18397, SPE 20007, SPE 20009