This report attempts to establish the effects, if any, of wellbore inclination on the performance of down hole gas separators. Different down hole gas separator designs have been extensively studied in the laboratory and far reaching conclusions have been drawn from observations made in the laboratory for vertical wellbores. However, it is pertinent to note that most wellbores are not truly vertical and a survey which shows the deviation of the wellbore from a vertical reference point is often present in most wellbore configurations. Hence, this thesis compares at similar operating conditions, the performance of different down hole gas separator designs installed in both a vertical and inclined wellbore configuration. Technology has made it possible to drill horizontal wells which are fast becoming ubiquitous in most oilfields. With gravity forces dominating separation in static down hole gas separators; it is certainly logical to study the effect of wellbore inclination on the separation efficiency of down hole gas separators as transport properties of multi-phase fluids are affected by gravity. With the above mentioned arguments, it becomes imperative to study down hole gas separators under conditions which best simulate oilfield operations. The approach utilizes an instrumented full scale model of an inclined well-bore and separator constructed with clear acrylic pipe. The base case consists of the entire wellbore and separator set up installed vertically and subsequent experiments were performed with the wellbore inclination angle at 45°. An air and water mixture is injected through the well's perforations. The air and water flow rate measurements define a performance plot of each separator design with respect to wellbore inclination. Continuous flow conditions were applied in all tests. Results obtained from laboratory annular bubble rise experiments show that in an inclined set up, the bubbles tend to move along the walls of annulus (the upper part of the annulus wall) where the effect of drag is maximum. Results from the annular bubble rise experiments in an inclined wellbore equally show that the upwards motion of the smaller bubbles (bubble size diameters less than 0.25 in.) tend to be considerably reduced by drag while on the contrary, the larger bubble (Taylor type bubbles) have higher velocities along the upper walls of the annulus. Also, results from the down hole gas separator performance tests conducted indicate that at similar operating conditions of 800BPD/105MSCFD, a gravity driven downhole gas separator installed in a wellbore inclined at 45° would perform better (by 46%) than the same gravity driven downhole gas separator in a vertical wellbore. While at similar operating conditions of 650BPD/105MSCFD, a centrifugal force driven down hole gas separator installed in a vertical wellbore would perform comparatively with the same centrifugal force driven down hole gas separator installed in a wellbore inclined at 45° (less than 2% difference in separation efficiency).

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.