白云凹陷深水区井壁稳定性研究及应用

白云凹陷深水区是珠江口盆地重要的储量增长点,但是深水钻井安全钻井液密度窗口窄,钻井风险高,因此准确评估白云凹陷深水区井壁稳定性的规律和特点,对白云凹陷下一步的开发十分必要。针对白云凹陷深水区的钻井情况和地质特点,研究了地层压力体系特征,认为幂律模型和Eaton模型能够获得精度较高的地层密度和地层孔隙压力,得出了地层压力体系随水深的变化规律,其中地应力和破裂压力受水深影响明显。利用得到的地层压力对白云凹陷深水区的安全钻井液密度窗口进行了评估,认为白云凹陷深水区井壁坍塌风险较低,漏失风险高,主要是砂岩渗透性漏失,钻井液设计时需考虑其影响。

Research and application of deepwater wellbore stabilization in Baiyun Depression

Baiyun Depression is an important growth point of reserve in Pearl River Mouth Basin. However, due to the narrow fluid density vessel for safe deepwater drilling and high drilling risk, to accurately assess the regularity and characteristics of deepwater wellbore stabilization in Baiyun Depression is essential the further development of Baiyun Depression. Considering the drilling condition and geological characteristics of the deepwater drilling in Baiyun Depression, the paper studies the formation pressure system features and concludes that the power law model and the Eaton model can provide formation density and pore pressure with higher precision and further reveal how the formation pressure system varies with the water depth, in which the crustal pressure and the bursting pressure are significantly affected by water depth. The calculated formation pressure can be used to assess the fluid density vessel for safe deepwater drilling in Baiyun Depression and the results show that there is low risk of hole collapse but high risk of losses, especially sandstone permeability loss. The research results provide an important basis for the design of deepwater drilling fluid in Baiyun Depression.