欠平衡钻井技术在松辽盆地腰深1井中的应用

腰深1井是部署在松辽盆地长岭断陷达尔罕断凸带腰西构造高点上的一口直探井。该井储集层具有典型的低孔隙度、低渗透率特征,常规钻井容易引起储层伤害,造成气层产能下降,甚至不能发现气层。为此,在区域地质构造与岩性特征分析的基础上,论证了对该井实施欠平衡钻井的必要性和可行性,结合腰深1井的地质特征与井身结构参数,对欠平衡钻井实现方式、欠平衡压差、钻井液体系与性能以及欠平衡钻井参数等进行了设计。施工结果表明:欠平衡钻井技术保护了储集层,提高了钻井速度,延长了钻头寿命,钻进过程中发现了3套主力气层,达到了预期目标。该井欠平衡钻井技术的成功应用,验证和完善了欠平衡钻井设计和施工理论与方法,有助于欠平衡钻井技术的进一步应用和推广。

Application of underbalanced drilling technology in Vaoshen-1 well in the Songliao Basin

The Yaoshen 1 well is a vertical exploratory well planned at the high point of Yaoxi structure at the Da'erhan uplift in the Changling Depression of the Songliao Basin. The pay zone here is featured by low porosity and low permeability so the reservoir is easily contaminated by conventional drilling, which results in the decrease of productivity of the pay zone and even leads to the failure in reaching the target zones. In view of this, based on an analysis of regional structures and petrophysical features, the necessity and feasibility of underbalanced drilling (UBD) in this well is demonstrated. Then, taking the geological features and the casing program parameters of the Yaoshen 1 well into consideration, the UBD concrete measures, underbalanced pressure differences, drilling fluid systems and fluid properties, and UBD parameters are all well planned. The field application indicates that the planned UBD technology not only protected the reservoir, but increased the ROP and prolonged the bit's service life, and finally the expected 3 major gas zones were achieved. This success verifies and improves the UBD planning method and further promotes its wide application.