| Steam assisted gravity drainage(SAGD)technology has been successfully applied to develop oil sands resources in Canada and is becoming more and more mature.However,oilfield production has demonstrated that reservoir heterogeneity has a serious impact on SAGD development,among which the most drastic impact is caused by multiple barrier layers in the reservoir.There are two main manifestations: first,the direct influence of barrier on fluid flow;second,the indirect influence on SAGD production dynamics.Therefore,it is urgent to carry out research on the variation characteristics of SAGD productivity considering multiple barrier layers.This paper takes the L oil field of Canada as the prototype to carry out a numerical simulation study on the impact of the barriers.Firstly,based on the typical single barrier,the steam chamber development and crude oil drainage of SAGD under the influence of different barrier properties,distribution locations,sizes,reservoir thickness and physical properties were studied.After comparing the production dynamics with the development of steam chamber,the influence of barriers on productivity was evaluated by using peak productions,and the main control factors were analyzed.Secondly,the quantitative impact of multiple barriers on SAGD development productivity was explored.The fluid flow in the steam chamber was analyzed by decompressing the multiple barriers into double barrier units.In the aspect of productivity,the multiple barriers are classified according to the barrier width,and the productivity variation characteristics of the barriers with equal width and barriers with unequal width are discussed in detail.Finally,the influence of formation heterogeneity along the long horizental well on SAGD development under the condition of multiple barriers is analyzed.The effect of multiple barriers is further simplified by using the influence effect equivalent method.Under the condition of non-uniform steam absorption along the well,the influence of A,B and C combination of different barrier-bearing reservoir modes on SAGD production in L oilfield was analyzed.Different portfolios were evaluated from three aspects: peak production,duration of upper production period and cumulative oil production.The research results in this paper further improve the influence of barriers on SAGD production,provide a new way to evaluate the productivity characteristics of SAGD under the condition of multiple barrier layers,and play a certain guiding role in oilfield field development. |
