水平页岩气井油管下深对排采效果的影响

Influence of end of tubing on deliquification in horizontal shale gas wells

页岩气井及时采用油管生产能够有效地保证气井的稳定递减,但油管下至哪个位置对气井稳产最有利,井身轨迹对该位置是否有影响尚无深入研究。为了确定油管的合理下入深度,通过水平井全井筒试验装置的气水流动实验,对油管下深至积液水平段、斜井段不同位置处(水平段和斜井段分别积液情况时,油管下深至斜井段上端、水平段跟端、水平段1/3处、水平段2/3处及水平段趾端)试验管段内的积液特征以及出口排液量进行了分析。结果表明,水平段下倾时,油管下入斜井段携液气体液量最小,水平段上倾且油管下入水平段1/3处携液气体流量最小。然后利用全动态多相流模拟系统OLGA,以威204HX平台几口井的气井产能方程、气井井身结构、地层压力下降梯度作为基本参数,对不同井身轨迹时油管不同下深对应的气井生产过程的井筒积液进行了模拟。结果表明,水平段上倾累计产气量大于水平段下倾累计产气量,水平段上倾且油管下入水平段1/3处气井的累计产气量最大。综合分析,油管下入水平段1/3附近对水平页岩气井排采最为有利。

Timely tubing production in shale gas wells can effectively ensure the steady decline of gas wells,but the location of tubing is the most favorable for stable production of gas wells,and whether the well trajectory has an effect on this location has not been thoroughly studied.In order to determine the reasonable end of tubing(EOT),firstly,the tubing was lowered to different positions in the horizontal and inclined sections of the fluid(in the case of fluid accumulation in the horizontal section and the inclined section respectively,the depth of the tubing reaches the upper end of the inclined section,the heel end of the horizontal section,1/3 of the horizontal section,2/3 of the horizontal section and the toe end of the horizontal section);Then,the characteristics of liquid accumulation in the test section and the liquid discharge at the outlet are analyzed through the gas water flow experiment of the whole wellbore test device of horizontal wells.The results show that when the horizontal section inclines upward and the end of tubing reaches 1/3 of the horizontal section,the gas flow carrying liquid is the smallest.Finally,the well productivity equation,well structure and formation pressure gradient of several wells on the platform of Wei 204HX were taken as the basic parameters to simulate the fluid accumulation in the production process of gas wells with different well trajections and different depths of tubing by the full dynamic multiphase flow simulation system OLGA.The results show that when the horizontal section inclines upward and the end of tubing arrives at 1/3 of horizontal section,the cumulative production of gas wells is the largest.Based on comprehensive analysis,it is most favorable for horizontal shale gas wells when the end of tubing is about 1/3 of horizontal section.