裂缝性储层最大下钻速度确定

Defining Maximum Down Drill Speed

针对塔中Ⅰ号气田碳酸盐岩储层压力敏感、孔隙发育,安全密度窗口窄,一般为（1.20 g/cm3～1.23 g/cm3）.当下入钻具过快使井内液柱压力大于地层压力时,钻井液很容易透过裂缝、孔隙、裂缝一孔隙、溶洞发生漏失,这种情形下的漏失往往是有进无出,导致循环失返.通过建立地层破裂压力和瞬态波动压力模型,求出不同泥浆密度的下钻速度.文章以TH62-X井为例预测了不同井深处下钻速度.

The sensitive pressure, porosity development, narrow safety density window （ 1.20 g/cm3 ~1.23 g/cm3 ） of tower I field carbonate reservoir cause the outflow of drilling fluid through voids andcrack when the drilling column pressure overstep reservoir pressure is caused by the greater downdrill speed. Under such circumstances, the loss of circulation return is usually caused by drilling flu-id leakage. The establishment of the transient formation fracture pressure and pressure fluctuationmodel helps to calculate the down drill speed of different mud density. The paper takes well TH62-X as an example to predict the speed drill wells of different depths.