可循环微泡钻井液研究及其在乍得潜山地层的应用

乍得潜山地层微裂缝发育丰富，地层压力系数在1以下，采用常规钻井液体系往往导致地层发生恶性漏失，针对该技术难题，提出采用可循环微泡钻井液钻潜山储层。合成出一种可用于可循环微泡钻井液的发泡能力强同时具有稳泡能力的发泡剂GWFOM-LS，在120、150℃时0.5% GWFOM-LS的发泡体积分别为720 mL和400 mL以上，其抗温能力达到130℃，抗盐能力达10%，抗钙能力达0.5%。基于该发泡剂优选出密度范围在0.70～0.96 g/cm3的可循环微泡钻井液体系。该体系在乍得Baobab C1-13井裂缝发育的潜山油层进行了应用。现场应用表明，该发泡剂配制的可循环微泡钻井液性能稳定，而且具有较好的携岩性能和储层保护性能，利于井下工具信号传导，解决了钻井过程中潜山地层恶性漏失问题，为今后潜山储层开发奠定了技术基础。 

Recyclable Micro Foam Drilling Fluid: Its Study and Application in Burial Hill Structure in Chad

The burial hill structure in Chad has micro fractures that are quite developed and the formation pressure coefficient is generally less than 1.0. Using conventional drilling fluids, severe mud losses are inevitable. To avoid mud loss, recyclable micro foam drilling fluid has been adopted in burial hill drilling. This drilling fluid was first developed in laboratory with a high performance foaming agent GWFOM-LS, which also was also a foam stabilizer. GWFOM-LS is resistant to high temperature (130℃), high salinity (10% NaCl) and high calcium (5 000 mg/L). The micro foam drilling fluid developed has density adjustable between 0.70 g/cm3 and 0.96 g/cm3, and has been used successfully on the well Baobab C1-13 in Chad. The recyclable micro foam drilling fluid showed stable properties in field applications, good cuttings carrying capacity and reservoir protecting performance, satisfying the needs for safe drilling operation. Electric signal transmission through the foam was satisfactory, and severe mud losses in burial hill drilling were resolved. All these successes have laid a solid foundation for burial hill reservoir development.