微米刚性氧化石墨烯颗粒的制备及协同堵漏性能评价

Preparation of micron rigid graphene oxide particles and evaluation of synergistic plugging properties

泸州区块深层页岩气地层微米级裂缝发育,且偶有天然裂缝存在,结构面节理特征弱,钻井过程中,容易造成滤液侵入地层,引起井壁坍塌,亟待研制一款能抗压抗高温的微米尺度刚性封堵剂,既能应对微米裂缝带来的威胁,又可以与大片径堵漏剂有很好的协同堵漏作用。采用改进Hummers法制备氧化石墨烯(GO)水凝胶,经超长时间高温真空干燥之后,将其粉碎,获得了一种刚性氧化石墨烯颗粒(GO-RP)。这种颗粒属于氧化石墨烯纳米片的多重叠加,用超声波无法使之分散,单体能够承受215℃以下的温度。采用可驱替式堵漏仪评价这种颗粒的协同堵漏性能,实验结果表明,GO-RP可在压力作用下不断地冲进裂缝孔隙进行填充,搭配混合堵漏剂,尤其是带有柔性纤维的材料,能够形成更致密的承压封堵层,承压能力高达9 MPa,降漏失率提升了约70百分点。将封堵剂GO-RP加入水基钻井液中,可使钻井液漏失量显著降低,同时,在高温下仍能保持较好的摩擦性能和抗压能力。这种刚性氧化石墨烯颗粒封堵剂在钻井堵漏领域有良好的应用前景。

Aiming at the development of micron-scale fractures accompanied by occasional natural fractures in the deep shale gas formation of Luzhou block,and the weak nodal characteristics of the structural surface which can easily cause filtrate to intrude into the formation and lead to wellbore collapse during well drilling,there is an urgent need to develop a micron-scale rigid plugging agent capable of resisting pressure and high temperature in order to cope with the threat posed by the micron fractures,which can have a good synergistic plugging effect with the large-size plugging agent at the same time.The graphene oxide(GO)hydrogel was prepared by the modified Hummers method and then crushed after ultra-long-time high temperature vacuum drying to obtain rigid graphene oxide particles(GO-RP).These particles belong to the multiple superposition of graphene oxide nanosheets which could not be dispersed by ultrasound,and the monomers were able to withstand temperatures up to 215℃.Displaceable plugging instrument was used to evaluate the synergistic plugging properties of this particle,and the experimental results showed that GO-RP can keep rushing into the fractures and pores to fill under pressure,and with the mixing of plugging agent,especially the material with flexible fibres,it can form a more dense pressure-bearing plugging layer,with a pressure-bearing capacity of up to 9 MPa,and leakage rate reduction was improved by about 70 percent.Adding the plugging agent GO-RP into the water-based drilling fluid can significantly reduce the leakage of drilling fluid.Meanwhile,GO-RP can still maintain good friction performance and pressure resistance under high temperature.This graphene oxide rigid particles plugging agent has a good prospect in the field of drilling leakage plugging.