State of the Industry in CO2 Floods

Abstract

Abstract Every other year the Oil and Gas Journal presents a summary of worldwide enhanced or improved oil recovery (EOR or IOR) methods and current production. Other papers review EOR technologies and present usage, both in the US and worldwide. Our intent was not to duplicate this type of documentation but to review CO2 as a maturing EOR process and to assess what was going well in the field as well as what was not going well, to identify research opportunities, and to develop correlations between problems encountered and solutions developed. A survey was sent to a number of engineers responsible for day to day operations of CO2 floods. This paper reviews the response received concerning 25 projects. Represented in the responses are experiences from 25 fields by 19 different engineers employed by nine oil companies. Introduction Oil recovery in the US from EOR processes peaked in about 1992 with thermal methods peaking in 1986 and decreasing by about 10% since. EOR from CO2 has continued to increase. In 1996 oil production from CO2 represented more than 170,000 b/d, up from 28,000 b/d in 1986. This represents a relative contribution of 24% versus 5% of the total EOR in the US, respectively. Even though the total EOR oil is not increasing as rapidly as it did a few years ago it continues to represent an ever-increasing percentage of shrinking domestic production. The bulk of production from CO2 remains in the Permian Basin, but successful projects outside that area have proven the wide applicability of the process. Of all the EOR methods, only CO2 is at an all-time high in the number of active projects, with good prospects continuing to be identified and developed each year Successful projects have been documented in Colorado, Louisiana, Mississippi, Oklahoma, Texas (within and outside the Permian Basin), Utah, and Wyoming. As CO2 supplies become more available, a greater number of projects are anticipated throughout the US. As some of the larger floods mature, the importance of applying CO2 to smaller fields will increase in coming years. As part of an ongoing effort to service the CO2 EOR industry the following questions were asked of a number of project engineers in the US:What has gone well with the project?What has not gone well with the project?What has been your strategy and why was it selected?Is the project considered a technical success?Is the project considered or expected to be an economic success?What could have been done differently to improve the economics?Anything else you would do differently if starting your flood today?What has been learned from this project that could be important to other CO2 projects?What are the mysteries of your flood?Where should future studies and research focus?What is the current project CO2 utilization value and the best guess for the final value?Approximate current total oil production rate and improved oil production rate? The comments received regarding each of the CO2 floods are summarized in Tables 1 through 11 at the end of the paper. The following sections discuss each of the questions and the responses received. What has gone well with the project? Table 1 summarizes what has gone well for the CO2 projects surveyed. In every case except one that was too early to tell (TETT) there has been incremental oil production. In thirteen cases adjectives such as "good," "significant," "large," "excellent," or "met expectations," were used to describe the oil production. Two fields referred to a quick positive response to CO2 injection. P. 81^