Integrated Process Modeling: Drivers, Enablers and Case Study

摘要

The choice of an integrated process modeling approach is function of information availability, datarnuncertainty, and the cross-discipline integration demand. Based on these parameters, the modularity, thernmultidisciplinary knowledge request, and the decision between feedforward or feedback control isrndefined. First, this paper discusses drivers and enablers to implement field life cycle management. To thisrnend, right decisions are necessary to ensure that integrated asset optimization reaches the global optimumrninstead of local ones. The second part of this paper presents a case study describing a compositionalrnproduction stream modeling to perform multiple flash calculations from the initial reservoir to thernstock-tank conditions. The integration objective is to deliver robust fluid characterization to model thernmultiphase flow expansion process through a surface choke valve at the wellhead.rnThe surface separation process was defined as two stages: a high pressure stage and the stock-tank. Thisrnprocess represents the well testing route scenario. SRK-EOS previously tuned with PVT data was used forrnfluid characterization. The initial gas cap composition was generated from the oil flashed at the reservoirrnsaturation pressure and temperature. The original oil composition, at initial reservoir condition, was usedrnfor the fluid initialization. A recombination method calculated the wellbore composition at depletedrnpressure and temperature by an iterative logic. In this procedure, the gas cap, the reservoir oil, and thernwater mole fractions were blended to match the production gas/oil ratio and water cut from the well. Thernoil and gas density at stock-tank condition, the oil flow rate at separator condition, and the separator oilrnformation volume factor were used as simulation validation parameters.rnA multi-rate well test was performed in real field scale to provide input data for the investigation. Thernmulti-rate well test consisted to execute a sequential step response disturbance. Each disturbance wasrnfollowed by a transient and a steady state period u0002a prioriu0002 to a next step. Two types of well performancernwere analyzed: production with stream composition variation caused by near wellbore reservoir gas/waterrnconing and production with constant stream composition. The simulation was implemented in the softwarernHysys from Aspentech to provide the fluid properties and the stream composition for modeling thernmultiphase flow expansion process through a choke valve in wellhead conditions.rnThe results demonstrated that multiphase flow expansion process through the valve is neither isenthalpicrnnor isentropic. For the outlet valve (downstream choke) temperature calculation, it was found anrnabsolute relative error of 8% for the isenthalpic flash and 14% for the isentropic flash. These errorsrncorresponded to the higher pressure drop across the valve. The agreement between calculated and measured valve outlet temperature was achieved when equilibrium calculation considered an adiabaticrnefficiency coefficient (ηeff) to correct the flow thermodynamic path assumption through the valve. Finally,rna parameter sensitivity analysis is presented to determine how the flash input variables influence thernadiabatic efficiency (ηeff) behavior.