南海莺琼盆地高温高压井堵漏技术

Plugging Technology for HTHP Wells in the Yingqiong Basin of the South China Sea

南海西部莺琼盆地地质条件复杂,井底温度和压力高,钻进目的层过程中井漏频发。为解决井漏问题,在分析发生井漏主要原因的基础上,提出了将耐高温刚性堵漏材料和耐高温弹性堵漏材料相结合的思路。在钻井液中添加耐高温刚性堵漏材料DXD和耐高温弹性石墨堵漏材料TXD配制成堵漏浆,DXD在诱导裂缝中架桥,TXD在压差作用下充填于诱导裂缝剩余孔隙中,防止诱导缝进一步开启扩大,封堵诱导裂缝,提高地层承压能力。室内性能评价表明,堵漏浆密度最高可达2.40 kg/L,抗温能力可达200℃。堵漏浆在莺琼盆地多口高温高压井进行了应用,堵漏效果较好,堵漏成功率由采用常规堵漏技术的30%左右提高到了80%以上。这表明,该堵漏浆可以封堵莺琼盆地目的层的诱导裂缝,提高地层的承压能力和堵漏成功率,解决井漏频发的问题.

The Yingqiong Basin in western South China Sea is characterized by complex geological conditions,high bottomhole temperatures and pressures,and lost circulation which occurs frequently during drilling into the target layer.In order to solve the problem of frequent lost circulation in target layer,the main causes of lost circulation were analyzed,the idea of combining the high temperature resistant rigid plugging materials with high temperature resistant elastic plugging materials was followed,and a plugging slurry was prepared by adding DXD(a high temperature resistant rigid plugging material)and TXD(a high temperature resistant elastic graphite plugging material)into drilling fluid.The performance evaluation showed that the density of plugging slurry could reach 2.40 kg/L and the temperature resistance could reach 200℃.The DXD could form bridges in the induced fractures,while the TXD could enter the residual pores of induced fractures under pressure difference,preventing the induced fractures from further opening and expanding,blocking the induced fractures and improving the pressure-bearing capacity of formation.This plugging slurry had been applied in several high temperature and high pressure(HTHP)wells in the Yingqiong Basin with the success rate of plugging increasing from 30% to 80%,indicating that the plugging slurry could block the induced fractures in the target layer of the Yingqiong Basin,improve the pressure-bearing capacity of formation and the success rate of plugging,and solve the problem of frequent lost circulation in the target layer.