Study On The Design Methods Of Continuous Gas Lift

Continuous gas lift is a kind of gas lift production, this kind of artificial lift method is to the tubing casing annulus continuously injection of high pressure gas, mixed gas and fluid in wellbore, resulting in reduced mixture density of the wellbore, thus leading to the bottom hole flowing pressure is reduced, the producing pressure drop increases, will be lifted to a wellbore fluid to the ground lifting method that it is similar to the natural flow. Adaptation range of continuous gas lift is very wide for fluid properties, yield ranges and lifting height. There is good adaptability for continuous gas lift, has the following characteristics:(1)The yield has a wide adaptive range and can adjust to the adjustment of the production on the ground;(2)Fewer moving parts and longer service life, can realize not to move the column in the three years;(3)Replacing the gas lift valve by the slick line operation, and maintenance is convenient;(4)The relevant completion string can realize the task that is testing, killing the well and snubbing service;(5)Strong ability to adapt to the environment, and is not affected by sand, gas, well deviation and bad land surface environment;(6)The operation is simple, and the production is easy to realize centralized management and automation, and has a low operation cost.In general, it needs to take gas lift design before the continuous gas lift. The gas lift design cannot leave the guidance of the theory, therefore, it is necessary to study on the design method of continuous gas lift. Study on the accurate gas lift design method need to obtain the following information: well depth, tubing size, casing size, well performance conditions, surface line size and length or given tubing head pressure, hoping to get the output, containing water, input gas relative density, can provide the gas injection pressure and gas flow rate, the inflow performance, oil temperature, ground temperature, ground flow oil density, formation water density, killing fluid density, gas density, formation pressure, gas/oil ratio and viscosity of crude oil and so on. The most of above data will be directly used for the design, individual items are used as a reference in the design.Therefore, the design of gas lift method is the key content of gas lift technology, and using the appropriate design method can make the gas well to work better, to achieve optimal yield of gas lift well. In this paper, studying the most commonly methods of the design method of continuous gas lift,that is, variable flowing pressure gradient method, equal gas injection pressure drop method and equal closing pressure drop method, and carrying on the comparative analysis to the three kinds of methods, then to choose the PIPESIM that it is based on equal closing pressure drop method to compose B formation in Y oilfield. Through the theory guides practice, field practice to deepen the theory, and the oil wells product at maximum capacity . First of all, the paper investigates the current situation of continuous gas lift design at home and abroad; secondly, to research the most commonly application three kinds of methods of continuous gas lift design, giving the design process of these methods and the applicable conditions; Then, equal close pressure drop method is used to design for gas lift wells, through the theory and practice predict artificial gas lift replacing time, on the basis ,the gas injection pressure were optimized and predicted the gas injection rate, got the gas lift design results such as the number and depth of gas lift valve; Then to optimize distribution for gas lift ,it is based on gas lift performance curve, and sensitivity analysis for sensitive parameters such as gas injection pressure and wellhead pressure, we can optimize the design of gas lift, and ultimately improve the yield and cost saving.