Miscible Flooding Gas Tracer Production Curve Interpretation Method Study

Well-to-well gas tracer technology can get quantitative information of underground liquid distribution, can evaluate the efficiency of miscible displacement reservoirs, and can also provide petroleum engineers reasonable measures for controlling the reservoir performance and building relative correct geologic model. As the inherent uncertainty in the field development of miscible displacement, well-to-well tracer technology has been widely used to provide quantitative information, and accordingly to obtain better reservoir description.In our country, tracer technology has widely used in the water displacement reservoirs, but it was hardly used in the gas displacement reservoirs. The gas tracer technology for testing and interpretation is only in the initial stages. Although much tracer model and the interpretation procedure were reported, none involved the gas tracer responds. In recent years, some reservoirs suitable for miscible displacement have been discovered in the western part of China. In order to effectually develop these reservoirs, it was necessary to investigate the gas tracer's partition and retention character and its flow mechanism in the reservoir porous medium. Furthermore, the response curve of gas tracers in the miscible displacement should be quantitatively interpreted to obtain the reservoir characteristic.In this dissertation, the influence of retention mechanism on the flow of the gas tracer was studied by the research for the gas tracer's partition and retention character in the reservoir liquid. On the basis of Abbaszadeh-Brigham method, the streamtube model of the gas tracer flow and breakthrough equation in the well pattern was established. What's more, a nonlinear optimization technique is used to analyze gas tracer profiles in the miscible displacement reservoir. And the Dykstra-Parsons coefficient was introduced to help obtaining the reservoir parameter, such as number of plies, porosity, permeability and thickness. As a result, software was compiled to interpret gas tracer profiles in the miscible displacement reservoir. The contrast analysis was carried out between the interpretation method and the numerical simulation in the WAG miscible displacement pilot test in the Pubei Oilfield, the result approved the validity of this method.