Study on Mechanism of Shear Swirling Flow Vibration Cementing Improving Displacement Efficiency in Horizontal Well

When horizontal wells cementing, drilling fluid is easy to be held up at the narrow clearance due to casing eccentricity. At the same time, the density difference makes the lighter drilling fluid gather in the upper portion of borehole. Drilling fluid is hard to be displaced cleanly. Shear swirling flow vibration cementing technique is a new effective cementing technique, which can improve the cementing quality in several ways. On the one hand, shear swirling flow vibration cementing technique makes the annular fluid swirling flow. The circumferential velocity increases a circumferential shear stress for borehole wall, making it easy to carry drilling fluid near the wall and scour mud cake on the wall. Especially for the displacement at narrow clearance caused by the casing eccentricity in horizontal well, the effect will be more obvious. On the other hand, shear swirling flow vibration cementing technique makes the casing string periodically eccentric revolution. It changes the conventional pressure distribution and forms pressure difference on the annular cross section. The pressure at wide clearance is greater than that at narrow clearance, which is advantageous for the fluid flowing from wide clearance to narrow clearance and makes drilling fluid at the narrow clearance displaced effectively. In the paper, it analyzed the mechanism of shear swirling flow vibration cementing improving displacement efficiency from swirling flow and vibration two angles.