| Most of the wells in the gas field in Western Sichuan produce water and there is a risk of liquid loading.To explore the new drainage gas production technology,the downhole vortex drainage and gas recovery technology was introduced by the gas field in Western Sichuan in 2013.Compared with traditional drainage and gas recovery technology,this process has the advantages of low cost,convenient construction,and no harm to strata.However,The experimental results of two wells in the field show that the process does not achieve the desired results.The reason is possibly due to:(1)The influence of the structure parameters of the downhole vortex tool on the liquid carrying effect is unclear;(2)The lack of theoretical research on vortex drainage and gas recovery process design.For this reason,this article mainly carried out the following work:(1)The production parameters of oil pressure,water production,and gas production of 1,090 gas production wells in the gas field in Western Sichuan were statistically analyzed.The liquid carrying capacity of these gas wells was analyzed.A target gas well was selected based on the characteristics of eddy current tools.(2)Based on the theory of orthogonal design,the combination of 25 sets of tool structural parameters was calculated by numerical simulation method,and the optimal combination was obtained using the range analysis method.Based on Fluent software,the pressure field,velocity field and liquid volume distribution of the combined tool with optimal structural parameters were calculated and analyzed.(3)A set of visualized vortex drainage gas production simulation device with a height of 5 meters was set up.The vortex tool drainage experiment was carried out.The relationship of the pressure drop without and with 4 sets of combination tools with optimal structural parameters optimized by numerical simulation method was analyzed.The flows patterns before and after using the vortex tool were observed,and the pressure drop and the variation of the spiral distance under different gas-liquid ratios were observed.(4)By studying the law of the attenuation of the swirling flow,the distance of the swirling flow is divided into two phases:stability and instability,and the formula for calculating the corresponding distance of the swirling flow is given.A method for determining the reasonable penetration depth of the vortex tool combined with the swirling distance and the gas-liquid two-phase flow pattern was proposed,which provided a theoretical basis for the guidance of on-site design.(5)The process design of the X well in western Sichuan was completed,samples were processed,and field applications were carried out.The gas production per day increased by 900 cubic meters,and the fluid production per day increased by 0.2 cubic meters.The research results of this paper provide important technical support for the design of vortex drainage and gas recovery technology in the gas field in Western Sichuan,and also have certain reference value for the study of optimization design of structural parameters of various downhole tools. |
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