Well production optimization using streamline features-based objective function and Bayesian adaptive direct search algorithm

Well production optimization is a complex and time-consuming task in the oilfield development.The combination of reservoir numerical simulator with optimization algorithms is usually used to optimize well production.This method spends most of computing time in objective function evaluation by reservoir numerical simulator which limits its optimization efficiency.To improve optimization efficiency,a well production optimization method using streamline features-based objective function and Bayesian adaptive direct search optimization(BADS)algorithm is established.This new objective function,which represents the water flooding potential,is extracted from streamline features.It only needs to call the streamline simulator to run one time step,instead of calling the simulator to calculate the target value at the end of development,which greatly reduces the running time of the simulator.Then the well production optimization model is established and solved by the BADS algorithm.The feasibility of the new objective function and the efficiency of this optimization method are verified by three examples.Results demonstrate that the new objective function is positively correlated with the cumulative oil production.And the BADS algorithm is superior to other common algorithms in convergence speed,solution stability and optimization accuracy.Besides,this method can significantly accelerate the speed of well production optimization process compared with the objective function calculated by other conventional methods.It can provide a more effective basis for determining the optimal well production for actual oilfield development.

A NOVEL METHOD FOR CHARACTERIZING THE WHOLE PROCESS OF POLYMER GELATION

A novel method was established to investigate the gelation process of polymers. The change of refractive index of a polymer system during gelation was determined in situ in a prismatic cell. It can give reliable information on the whole gelation process. The apparatus and the execution of this technique are illustrated and the error is also discussed.

IN SITU INTERFEROMETRIC STUDY ON THE GELATION PROCESS OF POLYACRYLIC ACID GELS

In situ interferometry was used to investigate the gelation process of polyacrylic acid (PAA) gels. The basic principle of the in situ interferometry technique is illustrated. It can give sufficient information for non-destructive and successful investigation of the whole gelation process. The effect of initiator concentration on the gelation process was studied. The polymerization rate of AA increases with increasing initiator concentration. The error arising from the thermal effect in the gelation process can be neglected.

Dynamic response analysis of airport pavements during aircraft taxiing for evaluating pavement bearing capacity

In this paper,we propose a new method to analyze airport pavement bearing capacity using vibration in runways during aircraft taxiing.The new method overcomes shortcomings of existing tests,such as flight suspension and simulated loading.Between aircraft take-off and landing,acceleration sensors are arranged on the surface of the pavement far from the centerline,and the in-situ responses of the pavement under aircraft loads are collected during aircraft operations.The fundamental frequencies of the pavement are obtained by fast Fourier transformation of the measured accelerations,and are used to modify the parameters of a pavement finite element model built according to a design blueprint.By comparing the fundamental frequencies of the measured and calculated signals,the soil modulus is back-calculated.To implement this test method and ensure the accuracy of bearing capacity evaluation,aircraft dynamic loads are obtained by solving dynamic balance equations of the aircraft-pavement coupled system,and the vibration response of the pavement and sensitivity analysis of the fundamental frequencies are introduced.The results show that the fundamental frequencies at the center of the pavement are basically the same as those at the far side on the cross section;the fundamental frequencies in the depth direction remain constant,but the amplitude of the frequency spectrum decreases.The effect of the soil resilient modulus on the vibration frequency is most significant.The fundamental frequency increases from 6.02 to 10.55 Hz when the soil dynamic resilient modulus changes from 91 to 303 MPa.The effects of surface thickness and base thickness on the vibration frequency are less significant,and there is minimal influence when changing the dynamic elastic moduli of the surface layer or base layer.Field test results indicate the efficacy of the method of vibration measurement at the pavement surface to estimate the layer modulus of airport pavement.