Study on sustained-release kinetics of intelligent tracer for water search in horizontal wells

Abstract

At present, finding and plugging water in horizontal wells has become both the main difficulty and also the key for the sustainable and effective development of horizontal wells. Intelligent tracer technology for finding water can directly indicate the position and intensity of water outlets in a horizontal interval and it has broad application prospects. Currently, however, the interpretation of this technology in the field assumes that the intelligent tracer in each section of the horizontal well is released at an equal speed, which reduces the reliability of interpretation results. In order to improve the interpretation model for finding water in horizontal wells with intelligent tracers, it is necessary to further clarify the controlling factors of intelligent tracer release and its variation law. Therefore, using an independently developed water-soluble intelligent tracer, macroscopic static and dynamic release experiments were carried out, as well as CT scanning microscopic experiments, and a one-dimensional sustained-release dynamical model of the intelligent tracer was established based on the microexperimental results. A static non-scour experiment showed that the polymer skeleton is the fundamental reason for the tracer's sustained release. A dynamic scour experiment showed that temperature and external scour flow rate are the main factors affecting the release of intelligent tracer and that the greater the temperature and scour flow rate, the greater the cumulative release amount. Microcosmic release experiments showed that the release of intelligent tracer is a process of gradual dissolution from outside to inside, as well as diffusion from outside, with an obvious dynamic interface. Furthermore, the results of the dynamic model analysis were in agreement with those of the macroscopic scour experiments. The results of this study confirm that the influence of temperature and scour speed on intelligent tracer release should be considered in the interpretation model of intelligent tracer water search in horizontal wells, and they provide guidance and have practical significance for expanding the application of these tracers in oil and gas field development.