柳林区块煤层气井生产动态及其影响因素分析

Analysis on production performances and influence factors of coalbed methane wells in Liulin Block

针对柳林区块煤层气井生产动态影响因素复杂,无法制订合理的增产措施等问题,分析了区内50余口井排采动态规律,探讨了不同类型井产出动态的影响因素。结果表明：区内气井以中低产井为主,初期见气快,后期产气量下降严重。水平井相比于垂直井、丛式井,产气量相对稳定高产。煤层厚度、水文条件是分别影响山西组、太原组煤层产能的主要地质参数,结合工程因素分析认为,区内煤储层敏感性较强,压裂规模以及储层损害是造成区内垂直井低产的主要原因。同时,提出相应的增产参数指标：加砂量大于35 m3,施工液量大于400 m3;排采初期控制液面下降速度为2~10 m/d,产气后套压为0.1~0.3 MPa,减少关井次数,停排采时间小于20 d。

According to complicated dynamic influence factors of coalbed methane well production in Liulin Block,rational production increasing measures and other problems were hard to be set up. The drainage and extraction dynamic law of over 50 wells within the block was analyzed and the influence factors of the output performances in different type wells were discussed.The results showed that the wells within the block were medium and low production wells mainly,the gas production at the initial period was high and the gas production was seriously reduced at the late period.Related to the vertical well and cluster well,gas production of the horizontal well would be stable and high.The seam thickness and hydrological condition were the main geological parameters affected to the production capacity of seams in Shanxi Formation and Taiyuan Formation individually. The further analysis combined with the engineering factors showed that the coal reservoir within the block was high in sensitivity and the fracture scale and reservoir damage were the main causes to cause the low production of the vertical well within the block. Meanwhile,the relevant index of the production increased parameters was provided： Sand added quantity would be over 35 m3 and the construction fluid quantity would be over 400 m3.A drop speed of the liquid level controlled would be2 ~ 10 m / d and a casing pressure after the gas production was 0.1 ~ 0.3 MPa.The number of the well to be closed should be reduced and the time to stop the drainage and extraction should be less than 20 days.