Research On Steam Chamber Expansion Of SAGD In Ultra-heavy Oil Reservoir

With the economic and social development of our country,the demand for petroleum resources has been increasing,and our country’s crude oil has a high degree of foreign dependence and is in a state of sustained growth.This caused great threat to the economic and social development and energy security of our country.China’s heavy and ultra-heavy oil resources are abundant.The exploitation of heavy oil and ultra-heavy oil has become a major strategic choice for ensuring China’s economic and social development and energy security.SAGD(steam-assisted gravity drainage)mining technology is currently considered to be one of the most effective means for exploiting ultra-heavy oils,due to its higher recovery,better economy,and higher reliability,it has been very widely used in the field of super heavy oil exploitation.The dynamic monitoring data of SAGD is abundant in the oilfield,but the lack of appropriate theoretical analysis techniques,the data utilization rate is low.At present,domestic and foreign scholars have focused on experimental and numerical simulations of SAGD mining in ultra-heavy oil reservoirs.There are also few SAGD temperature well test analysis technologies and there is no complete set of well testing theory and techniques for SAGD process.Therefore,it is very important to use the temperature test technology to study the expansion of the steam chamber.In this paper,the heat transfer theory of SAGD steam chamber expansion are studied firstly,a more realistic heat transfer model considering the variable heat transfer coefficient,a heat transfer model considering the thennal convection perpendicular to the steam chamber interface,and a heat transfer model considering the thermal convection at the interface of the parallel steam chamber were established respectively,the temperature distribution curve is plotted and the sensitivity analysis is performed;Then,based on the results of the heat transfer theory model,considering the characteristics of temperature changes in SAGD mining fonnations,a temperature well test model for the injection well temperature in the initial stage of SAGD and ’inverted triangle" temperature well test model in the mid-to-late of SAGD were established,and the typical type curves of temperature well test analysis were drew and the sensitive charateristics of type curves for model parameters were analyzed,the analysis method of steam wells for steam injection well test was also studied;Aiming at the temperature variation characteristics of SAGD monitoring wells,a temperature well test model for solving the SAGD monitoring wells for linear,nonlinear and two-zone composites were established,and the temperature test well pattern curve were drew and curve sensitivity were analyzed,and the analysis method of steam wells for monitoring well test was also studied.Finally,using the established temperature well test model,through well test interpretation and analysis,the interface shape of the steam chamber,the movement speed of the steam chambers interface,the physical properties of the formation,thermodynamic parameters,which further improve the eff-ective utilization of SAGD temperature monitoring data in the oilfield.The research results of this dissertation can guide the more efficient development of ultra-heavy oil reservoirs and obtain more economic benefits.At the same time,it has innovated and enriched the theory of SAGD temperature well test at home and abroad.