PCT Ltd. is working with Maverick Energy Services in Vernon County, Missouri, to use a unique electrochemically produced catholyte to enhance the injectivity, sweep efficiency, and oil production in a modified seven-spot well pattern. This seven-spot pattern #2A is a part of the larger Grassy Creek Oilfield where all seven wells are situated in the eastern part of the field and are closely spaced making them ideal for a field pilot test. These particular wells have not been treated other than by traditional waterflood. (Other wells in Grassy Creek were treated with a steam flood and a surfactant with limited success.) The pay thickness is between 20 and 25 feet for the lower Bluejacket SS and up to 80 feet in the Warner SS. The porosity in the Bluejacket is between 14-16% and 21-24% in the Warner. The permeability is between 20 and 40 md in Bluejacket and between 118 and 687 md (avg. 350 md) in the Warner. The crude oil is moderate to low gravity (19-29 degrees API), and reservoir temperatures average approximately 90 degrees F. The catholyte is produced onsite from special electroionizing process machinery using clean brine water. It can produce up to 700 gallons per day of 600-700 pm and 600-900 ORP catholyte. Storage is provided for up to 2000 gallons onsite, and a distribution line and pump is tied directly to the 2A seven-spot well injection well(s).
The project is using catholyte which has been initiated with Maverick Energy Services by designing up to an initial 30-day trial using varying volumes of the catholyte. The trial is being preceded by doing production and injection testing with fluorescent tracers on the two injectors (Warner and Bluejacket zones) as well as production tests on wells 2-1 through 2-6 to establish a baseline injection/production rate and pressure (if any since in the past some have gone on a vacuum), and monitoring every 4 hours for two to three days for tracer at each producer.
Once the baseline rates and pressures are established and the producing wells validated with positive or negative tracer shows, then the catholyte will be produced onsite and injected into the two injection wells or one injector depending on the results of the tracer testing for each zone. If all wells are not in communication with the injection well(s), then the issue will be addressed by considering polyacrylamide polymer as a small volume (250-500 gallon) pumped ahead of the next volume of catholyte to help slow breakthrough or channeling to certain wells and allow a more efficient distribution to the other wells. This may or may not be required to provide more uniform distribution of the catholyte in as many producing wells as possible on the seven-spot pattern. Once the injection profile is understood, then 1000 gallons of the (hot) 600-900 ppm catholyte solution will be manufactured and injected into the appropriate 2A injection wells. Then the injectors will be returned to injection of normal brine and monitored on day two with bucket tests performed on each well that is producing, looking for improved oil cut in the WOR as well as any pressure changes. Samples will be collected at each producing well. Then on day three, another 750 gallons (hot) catholyte will be injected followed by putting the well back on injection with clean injection brine water. Injection will continue over the next 24 hours (day four) followed by the production and sample testing protocol as before. This will be followed on the fifth day by another 500 gallons of (hot) catholyte and injection over the next 24 hours to monitor production rates and pressures as well as WOR. If oil ratio begins to increase, then the seven spot can be maintained on injection and repeating repeating the catholyte injection sequence described above over the next several days up to 30 days if necessary. The goal is to prove the catholyte technology for this reservoir type by a markedly improved oil cut after two to four weeks injection of catholyte alternating with injection brine water mix).
The results will be evaluated, and it will be decided that the injection will be continued as catholyte alternating with brine water as may be required to maintain improved oil cut in the water oil ratio (WOR).