A study of a novel down-hole gas-liquid separator/connector

Development of shale assets in the United States has drastically increased the overall domestic oil production. This was achievable due to the advances in horizontal well drilling and hydraulic fracturing technology, which gave access to more reservoir rock and surface area. In addition, as wells declined in rate, artificial lift methods like the use of a beam pump, electric submersible pump (ESP), or gas lift physically helped bring the oil and gas to surface and extended the life of a well. Operational challenges such as containing costs to maintain ESPs and using beam pumps on high gas wells became significant factors in determining the economic viability of a well. In this study, we examined a method to improve oil and gas separation down-hole in the production tubing so that a beam-pump will lift primarily liquid to the surface. Simultaneously, the method ensures that an ESP will remain effective and not overheat, as reservoir pressure declines, to lift fluid to the depth of the separator. A gravity-based down-hole gas liquid separator/connector was constructed using three acrylic pipes, one set inside another, with the inner pipe intended to tie in to the production tubing. The outer two pipes acted together as a gravity separator and pump connector. Water and air was pumped at varying rates from the bottom to simulate the fluid an ESP would deliver to the separator/connector. A standing valve was built into the inner tube, and a rod with traveling valve was manually operated to simulate a beam pump. The water and air mixture was visually inspected inside the pump to determine the effectiveness of the separator. The point at which the separator will fail to keep gas bubbles larger than 0.25 inches from coming inside the pump was quantified using three function tests: 1) Allowable Gas-Liquid Ratio the separator will process, 2) Liquid Velocity falling down the middle tube of the separator, and 3) Annular Gas Superficial Velocity between outside and middle tube. After testing a variety of air/water rates through two different sized separators, the results showed that if a separator passed all three function tests for a given air/water rate, then it would successfully separate bubbles larger than 0.25 inches (approximately 6mm) from coming into the pump