气体钻井地层出水量与钻具黏卡风险预测模型

Formation water production and risk prediction model of stuck pipe during gas drilling

陈烨¹ 闫铁¹ 孙晓峰¹ 王克林² 张亚东³

东北石油大学石油工程学院，黑龙江 大庆163318 中国石油塔里木油田分公司油气工程研究院，新疆 库尔勒 841000 中国石化中原石油工程有限公司技术公司，河南 濮阳 457001

College of Petroleum Engineering, Northeast Petroleum University, Daqing 163318, China Oil and Gas Engineering Research Institute, Tarim Oilfield Company, PetroChina, Korla 841000, China Technology Company, Zhongyuan Petroleum Engineering Co. Ltd., SINOPEC, Puyang 457001, China

气体钻井过程中，地层出水将使环空岩屑状态发生改变，造成携岩困难、钻头泥包、堵塞井眼等严重的井下事故，因此必须弄清楚钻遇水层后，不同出水量情况下地层水和岩屑的相互作用情况及流型分布，有必要对不同时刻地层出水量进行预测。现阶段地层出水量的计算模型中普遍未给出井底流压计算公式，而井底流压又直接影响着地层出水量的大小，文中采用渗流力学中平面径向流模型，结合气体钻井井底压力公式建立了地层出水量预测模型，结果表明，计算出水量的井底流压就是水层顶界面的压力，给计算带来简便。以不同出水量情况下地层水与岩屑的相互作用情况及地层出水量预测模型为基础，引入工程岩土学中稠度的概念，将岩屑的黏着界限作为钻具黏卡的临界条件，建立了地层出水后钻具黏卡定量预测风险模型。据此计算井底泥包出现的时间，对现场气体钻井地层出水后的井底状况、钻具黏卡以及泥包出现的预测有一定的指导意义。

Formation water influx will make a big difference to cuttings′ state in annulus during gas drilling, which results in severe and complicated accident such as cuttings transport problem, bit balling, and even hole plug. Therefore, interaction between cuttings and formation water and their flow behavior in the annulus must be studied. Moreover, the calculation method of formation water production is also necessary. At the present stage, the equation of bottom hole flowing pressure, which has direct effect on water influx rate, is generally not provided in the established mathematic model. A prediction model for formation water production is established in this article using a combination of radial flow model with annulus pressure equation during gas drilling. Calculation result shows that the bottom hole flowing pressure in the model proposed equals to the pressure of aquifer top interface, making the calculation process simplified. Based on the interaction between formation water and cuttings, the formation water production model under different situation, the concept of consistency in rock and soil engineering, with the adhesion limit as critical condition of stuck pipe, quantitatively mathematic risk model of stuck pipe during gas drilling is built. With this model, the time of bit balling can be calculated, which is also significant to the prediction of bottom hole condition, sticking problem and bit balling.

10.6056/dkyqt201506028