Abstract
Considering the impact of fluid flowing into pump on sucker rod pumping system (SRPS) dynamic behaviors, an improved SRPS model with new boundary model is presented, which is a fluid-solid coupled model with the interactions among surface transmission, rod string longitudinal vibration, plunger motion, and fluid flow. A uniform algorithm is adopted instead of the mixed iteration algorithm for the surface transmission and downhole rod string vibration submodels, to reduce the difficulties of solving the entire SRPS model. The dynamic response comparison is executed between the improved model and the current model, and the results show that it will bring a calculation error on pump load and pump fullness if the progress of fluid flowing into the pump (PFFP) is ignored. Based on this improved model, a multitarget optimization model is proposed and the dynamic behavior of SRPS is improved with the optimized swabbing parameters.
Highlights
The sucker rod pumping system (SRPS) is widely used in oil fields
The dynamic response comparison is executed between the improved model and the current model, and the results show that it will bring a calculation error on pump load and pump fullness if the progress of fluid flowing into the pump (PFFP) is ignored
Ps phase 3 p = pd phase 4 where Log and Lg are the gas column length when plunger is arriving at bottom dead center and top dead center, respectively, m; up is the plunger displacement, m; Ls is the pump stroke displacement, m; Lp is the plunger length, m; μ is the fluid dynamic viscosity, pa⋅s; δ is the clearance between plunger and pump barrel, m; Dd is the pump diameter, m; ts and tt are the open time of standing valve and travelling valve, respectively, s; tu is the upstroke time; q is the liquid instantaneous leakage volume
Summary
The SRPS is widely used in oil fields. It comprises three parts: surface transmission unit converting rotational motion into linear motion, sucker rod string as a joint between surface and downhole, and reciprocating pump exploiting the oil (see Figure 1). ∫ttut ps phase 3 p = pd phase 4 where Log and Lg are the gas column length when plunger is arriving at bottom dead center and top dead center, respectively, m; up is the plunger displacement, m; Ls is the pump stroke displacement, m; Lp is the plunger length, m; μ is the fluid dynamic viscosity, pa⋅s; δ is the clearance between plunger and pump barrel, m; Dd is the pump diameter, m; ts and tt are the open time of standing valve and travelling valve, respectively, s; tu is the upstroke time; q is the liquid instantaneous leakage volume In this formula, the principle that the gas/oil ratio of clearance volume (the space volume when plunger arrives at bottom dead center) equals the gas/oil ratio of pump inlet is applied. An improved SRPS model is presented with the new downhole boundary model, considering the movement of fluid flowing into pump with gas instantaneous dissolution and evolution. The optimization program is applied on a test well, and the results are given before and after optimization
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