Study And Application Of Tracer Testing Interpretation Based On Streamline Simulation Method

Most of the conventional oilfields in China employ waterflooding for development,but due to the formation heterogeneity and the long term washing of the injected water,the water displacement would become uneven in the reservoir.As a consequence,the water cut would increase rapidly and the ineffective water cycling would become more and more predominant,and the ultimate oil recovery would decrease.In order to mitigate this phenonmenon,profile control measures are always conducted.However,the inter-well tracer tests are always performed before the profile control to obtain valuable information about the formation heterogeneity.Using the results of inter-well tracer tests to calculate the reservoir parameters is called the tracer testing interpretation.Firstly,the one dimensional convection-diffusion equation is solved and the tracer production model for in a homogenious five-spot pattern are derived.According to the superposition of the tracer production at different layers,the analytical interpretation software for tracer testing is developed.Then the streamline model for oil and water flow and its solution are presented,and the Pollock streamline tracking method are introduced so that the saturation equation and tracer concentration equation could be solved along the streamline.In addition,the general procedure to use streamline simulator Frontsim to interpret tracer testing are summarized,after which the sensitivity analysis are conducted to determine the influence of several factors on tracer concentration curve.Based on above theories,the self-developed analytical interpretation software and Frontsim software are employed to interpret the tracer testing result in S oilfield.Through the matching of tracer concentration curve,the key information of high permeability layers,such as permeability,thickness and pore radius,are acquired.Combining the flow field intensity,heterogeneity coefficient and injection efficiency,the extent of water breakthrough of the five groups are ranked,which is: F17?F22>F28>F19>F24.There exists different extent of interlayer heterogeneity and plane heterogeinity in the five groups: for those groups which mainly have plane heterogeneity,it is advised to inject polymer microsphere to adjust the displacement profile,and in the meanwhile adjust the production rate of all producers;whereas for those groups which mainly have inter-layer heterogeneity,it is advised to inject jel as profile control agent to seal the high permeability layer,thus the water allocation in other layers could be enhanced.