中文摘要：

深水钻井喷射下导管过程中,为预防导管安装不到位或导管承载力恢复时间过长,需要根据海底土质参数对喷射排量进行合理的设计。基于淹没水射流理论及海底弱胶结土质破坏准则,建立了满足破土能力的最小喷射排量计算模型。采用339.7mm导管进行了喷射下导管的模拟试验,分析了排量对水力破土效果及表层导管承载力的影响规律。结果表明：当喷射排量小于最小喷射排量时,导管下入速度缓慢;当喷射排量大于最小喷射排量时,导管下入速度随喷射排量增大快速增大;导管承载力随喷射排量增大呈指数降低,当喷射排量超过1.2倍最小破土排量时,导管承载力降低幅度达到最大。根据最小喷射排量计算模型和模拟试验结果,建立了基于＂水力破土能力、导管承载力＂双因素约束的喷射排量设计方法。在南海22口深水油气井的应用表明,采用该方法设计喷射排量,可以提高导管喷射下入效率,保证导管稳定。

英文摘要：

When conductors are installed in deepwater drilling through jetting, it is necessary to design jetting flow rate appropriately based seabed parameters so as to guarantee the proper installation of conductors and rational recovery time of conductor capacity. A computation model of minimum jetting flow rate for rock breaking was established according to the submerged water jet theory and the unconsolidated seabed failure criteria. Then a pilot simulation test was carried out on conductor （φ339.7 mm） installation by jetting to analyze the influential rules of jetting flow rate on seabed breaking and surface conductor capacity. It is shown that the lowering velocity of conductors would be slow when jetting flow rate is less than a minimum certain value. On the other hand, the lowering velocity of conductors would increase quickly with the increasing of the jetting flow rate. The conductor bearing capacity decreases exponentially with the increasing of the jetting flow rate and reaches the lowest when jetting flow rate is over 1.2 times of the minimum value. Based on the calculation model and simulation of minimum jetting flow rate, the jetting flow rate design method is established under the constraint of hydraulic seabed breaking capacity and con- ductor bearing capacity. It has been applied in 22 deepwater wells in the South China Sea and the installation efficiency of conductors from jetting is increased and conductor stability is guaranteed.