Study On Inter - Layer Interference Factors In Multi - Layer Conventional Heavy Oil Reservoirs At Sea

In the development of multi-layer reservoirs, the phenomenon of interlayer interference definitely exists. Due to the platform conditions and environmental factors, the exploration of the offshore heavy oil is currently restricted to conventional heavy oil that can be exploited via water injection, and often through the way of massive commingling. The significant difference of viscosity between water and oil in heavy oil reservoirs can result in making the interlayer interference phenomena more obvious, while the interlayer heterogeneity brought by lots of factors of the massive commingling makes the interferences even more serious.Aiming at these problems above, this paper studies about the laws of interlayer interference effects brought by the heterogeneity of the layer, in the process of conventional multilayer heavy oil reservoir.(1) In order to study the dynamic process of interlayer heterogeneity, starting from failure mining, this paper first split the production in pseudo-steady state, which is used for researching the process of interference occurrence, as well as the laws of interlayer interference effects brought by the interlayer heterogeneity.(2) The commingling and mining models for water-flooding wells are set up with the help of the Eclipse numerical simulation software. Comparing the factors of oil production rate, water production rate, contribution rate, recovery percentages and specific productivity index in the exploitation process, this paper analyzes the process of the interference brought by the heterogeneity, and finds the relationship between the differential of each factor and the interlayer interference coefficients.(3) Orthogonal experiments are designed to investigate the relationship between the interlayer interference coefficient and multi factors or some single factor. The interlayer heterogeneity representation system for this type of reservoir is found within different layers through multiple regression using the least square method.The following main achievements are made by this research:(1) In the development of commingling multi-layer reservoirs, the connection which is made by the well among different layers lead to a automatic pressure equilibrium which brings about the phenomenon of interlayer interference.(2) In the water injection development of commingling multi-layer reservoirs, due to the differences between each layer properties, the total fluid viscosity of the layers which absorb more water at the beginning drop more which make their seepage ability increase that intensified difference between the layers and interlayer interference.(3) In the water injection development of commingling multi-layer reservoirs, the water breakthrough of one layer will create serious interference to other commingling layers. Due to large differences in the viscosity of heavy oil reservoir water, water breakthrough in commingling multi-layer reservoirs will lead to more significant interlayer interference.The article offers an evaluation example of optimization schemes of the typical wells of Suizhong36-1Oil Field. The significance of interlayer interference influences of each scheme is assessed in the example, and it predicts every project using the reservoir numerical simulation model. The results show that the method used in this paper is superior to other methods, and that a brief and fast evaluation of the significance of interlayer interference of multiple factors in high permeable conventional heavy oil reservoirs, which is similar to Suizhong36-1Oil Field, using this method.