Improvements on existing wells' potential are crucial towards ensuring an economically viable project. Among various artificial lift techniques, gas lift is considered as one of the most efficient when associated gas capacity is available, and well production parameters are favorable. Also, jet pumps are specifically favorable for horizontal wells due to the relative ease in downhole installation. This paper combines these two techniques to introduce and evaluate an innovative hybrid method. It provides optimum operating windows for its design and application.
This study aims to introduce and benchmark a newly proposed hybrid lift techniques for horizontal wells. Some features of this method are: 1) The operating Gas Lift Valve (GLV) is installed at the bottom of vertical. 2) The jet pump is installed below the GLV. 3) The power fluid and gas are injected through the casing-tubing annulus. 4) The pressure of gas, provided by the compressor, is used to push the power fluid through the jet pump nozzle and into the tubing. An analytical model is applied to simulate this hybrid lift technique through nodal analysis, combining models for reservoir inflow, flow through jet pump, and two-phase flow in wellbore.
A sensitivity study is conducted to understand the effects of depth, API gravity, water cut, reservoir pressure, gas-liquid ratio (or gas injection rate), nozzle pressure, and nozzle and throat area ratio (R ratio) on the proposed hybrid lift's performance. A hybrid lift operating window is defined as the conditions that result in higher production rates than gas lift alone. The largest operating window is present for shallower wells with larger tubing diameters. The R ratio effects are variable throughout the cases and an optimal R ratio design is needed for each specific case. The required optimal GLR is observed to be always lower for the hybrid lift system compared to gas lift, making it relatively easier and cheaper to achieve. Overall, the operating window for application of hybrid lift is: 1) larger tubing size, 2) higher water cuts, 3) shallower wells, 4) lower required GLR's, 5) heavier oils, 6) higher nozzle pressures, 7) depleted reservoir pressures, 8) higher R ratios (if the well can handle the friction). Additional economic considerations are necessary to better evaluate this technique and determine its optimum operating window.
This innovative hybrid gas lift technique can be widely applied towards increasing well's performance, life, and economic viability. It shows its true merit in seemingly less promising and difficult cases with higher water cuts and lower reservoir pressures by increasing benefit throughout the life of the well.