Optimization Of Steam Injection Parameters For Heavy Oil Thermal Recovery

The horizontal well steam stimulation technology is widely used in the actual development of heavy oil reservoirs,and the quality of the steam injection effect directly determines the steam energy utilization rate,reservoir utilization degree and stimulation effect.This article aims to study the flow law of saturated steam in the whole well section,optimize steam injection parameters,and design steam injection schemes in combination with on-site wells.The steam flow in the vertical wellbore is a typical gas-liquid two-phase flow and heat transfer problem.Based on the pressure drop model and heat transfer model of the gas-liquid two-phase flow,the paper establishes a vertical wellbore saturated steam heat flow coupling model through the heat flow coupling method.On the basis of fluid dynamics software-assisted verification of the correctness of the model,the sensitivity analysis of wellhead parameters is carried out to discuss the influence of different parameters on the physical properties along the way.It is recommended to increase the steam wellhead dryness on site and determine the steam wellhead pressure and injection in combination with the actual situation.rate.There is a non-zero well angle between the flow direction of steam in the inclined wellbore and the direction of gravity,which reduces the pressure drop of gravity and increases the pressure drop of friction.Based on the vertical wellbore saturated steam heat flow coupling model,the influence of the well angle on steam flow and heat transfer is mainly studied,and the inclined wellbore saturated steam heat flow coupling model is established.Based on the verification of the model,the sensitivity analysis shows that the greater the inclination angle,the greater the pressure drop and loss of dryness along the way.In the horizontal wellbore,steam is injected into the formation through the steam injection valve,which belongs to the gas-liquid two-phase change mass flow problem with decreasing mass flow.Based on the gas-liquid two-phase variable mass pressure drop model and the wellbore-stratigraphic heat transfer model,we focus on the changes in steam parameters caused by mass loss and the law of formation steam quality and energy,and establish a coupled heat-saturation model for horizontal wellbore saturated steam.The accuracy of the model was verified by fluid dynamics software.At the same time,sensitivity analysis indicated that the increase in steam wellhead pressure and injection rate can effectively increase the formation steam absorption and improve the heel-toe effect.Based on the three-stage model of vertical wellbore,inclined wellbore and horizontal wellbore,the saturated steam flow model of the whole wellbore is established through the multi-stage coupling method.Considering the heterogeneity of the actual formation,on the basis of the coupled model of saturated steam heat flow in the whole well section of heavy oil thermal recovery horizontal wells,with the goal of improving steam injection efficiency and uniformly heating the formation,an optimized method of segmented steam injection parameters for horizontal wells is proposed.Through the application analysis of two wells in the field,it is pointed out that the optimization of the steam injection point position and steam injection valve parameters in combination with the permeability distribution characteristics of the production section can effectively improve the steam injection effect and increase the daily productivity of a single well.The steam flow model of the whole well section established in this paper theoretically improves the understanding of the steam flow law of the wellbore;it realizes the accurate calculation of steam parameters at any position in the axial direction of the wellbore.The sensitivity analysis of parameters and the optimization of segmented steam injection parameters for horizontal wells provide a design method and optimization guide for steam injection for actual production.