Perpustakaan Digital ITB

Pipe sticking is a critical drilling problem that can contribute to a high amount of Non-Productive Time (NPT). This study conducts an analysis of stuck pipe problem that occurred in Well A section 12-1/4” to determine its underlying cause based on the hydraulics parameters. Well A is an exploration directional well that experienced several problems which culminated in stuck pipe. The analysis revealed that the circulated mud weight was consistently below the pore pressure, causing borehole collapse. The borehole collapse caused severe washouts up to 21 inch in diameter. This borehole enlargement caused the annular velocity to drop below 60 ft/min, lower than the critical velocity needed to properly clean the well. Furthermore, the Rate of Penetration (ROP) and mud flow rate did not align with the industrial best practice. The ROP was too high, frequently exceeding 50 ft/hr, which was caused by underbalance condition that eliminates the chip hold down effect. Meanwhile, the mud flow rate was consistently below 650 gpm due to the problem in mud pump and mud tank. As a result, cuttings production was massive, while the drilling mud flow rate was inadequate to properly clean the wellbore. The failure to properly lift the cuttings resulted in the formation of stationary cutting bed, indicated by abnormal increase in Standpipe Pressure (SPP). The recalculation for Equivalent Circulating Density (ECD) was conducted and shows that the acquired ECD data was too low. From the analysis, it can be concluded that stuck pipe incident was caused by pack-off due to inadequate hole cleaning.