临兴致密气区块水平井套管优选的研究与应用

Research and Application of Casing Optimization for Horizontal Wells in Linxing Tight Gas Block

临兴致密气区块地层具有低孔、低渗、低压、低温的特征,自然产能低,需要经过后期压裂改造才能产出工业气流。随着中海油对致密气勘探开发力度的加强,临兴致密气区块钻井量剧增,钻井过程中套管费用在钻井总费用中的占比较大,所以,优选最合适套管对降低致密气整体开发成本具有重要的意义。通过中海油防腐图板和最大载荷法分别对套管腐蚀和套管强度进行分析和研究,结果表明,临兴区块不存在硫化氢,主要是CO_(2)腐蚀,由于CO_(2)含量较低,采用普通碳钢材质管材即可满足安全生产要求;同时,对不同极限状况下的套管强度进行数值模拟,选择17.4kg/m、P110级别生产套管可满足安全作业要求。

Linxing tight gas block has the characteristics of low porosity,low permeability,low pressure and low temperature,and its natural production capacity is low.Therefore,industrial gas flow can be only produced after post fracturing.With the strengthening of CNOOC’s exploration and development of tight gas,the drilling volume of Linxing tight gas block has increased sharply,and the casing cost accounts for a large proportion of the total drilling cost in the drilling process.Therefore,it is of great significance to select the most suitable casing to reduce the overall development cost of tight gas.Casing corrosion and casing strength are analyzed and studied by CNOOC anti-corrosion drawing board and maximum load method respectively.The results show that there is no hydrogen sulfide but mainly CO_(2) corrosion in Linxing block.Due to the low content of CO_(2),ordinary carbon steel pipe can meet the requirements of safety production;at the same time,by simulating the casing strength under different limit conditions,the17.4 kg/m,P110 Grade production casing proves to meet the requirements of safe operation.