Effect of Instantaneous Starting Pump on Fluid Transient Flow in Managed Pressure Cementing

The fluctuating pressure generated by the instantaneous starting pump of the cementing operation might easily cause formation fracture in narrow safety window formations. Accurate transient fluctuating pressure calculation and dynamically managed backpressure are required to achieve precise control of wellbore pressure in managed pressure cementing. Considering the transient flow characteristics of cementing fluids in the wellbore, unsteady transient friction, and the variation of high pressure-high temperature (HPHT) cementing fluid properties, a transient flow mathematical model of instantaneous starting pump during managed pressure cementing is established, and the method of characteristics is used for solution. Based on this, the established model analyzes the magnitude and variation of wellbore pressure under different model factors, temperature conditions, pump start durations, and target pump flowrates, which can achieve more accurate analysis of transient flow. The pressure and flow fluctuations generated during the instantaneous starting pump of cementing are significant, and the dynamically managed wellhead backpressure can effectively control the wellbore pressure in the narrow safety pressure window formations. This can reduce the risk of well leakage and provide reliable technical support for safe operations of instantaneous starting pumps during managed pressure cementing.