Research and Experiment on the Water Detection Testing Technology Using Segmented Tracers in Horizontal Wells

Abstract

In recent years, with the continuous increase in the intensity of oil and gas exploration and development, horizontal wells, as an important means for oil fields to transform the development mode, have seen a year-by-year expansion in their application scale, and their proportion of production capacity has been continuously rising. Due to the fact that the wellbore of a horizontal well is parallel to the oil reservoir, with the continuation of the production time, the water production problem has become one of the main factors plaguing production. Focusing on the technological objectives of low cost and rapid water detection, this paper proposes the technical idea of using the method of “tubing conveying + segmented packer sealing + tracer marking” for testing and detecting water in the production fluid profile of old wells. Each section of the horizontal well is separated by packers, and different types of tracer devices are placed in the corresponding intervals. During the production process, the tracers are released into the fluid. Through ground sampling and analysis, relevant oil/water information is obtained to determine the production location of oil/water. Based on the theories of solute dissolution and convection diffusion, a release model of tracer-coated spheres for water detection testing is established, and two tracer interpretation models for water detection testing methods are formed, namely the steady-state method of direct scouring without well shut-in and the transient method of scouring with a tracer slug during well shut-in. These models lay a model foundation for the qualitative and quantitative judgment of the water production section and the fitting calculation of the water production contribution rate of each section, thus forming the tracer marking water detection testing technology. This technology has been field-tested in three horizontal wells of the Changqing Oilfield, and the main water production locations have been identified. Research and field tests show that the segmented tracer water detection technology is technically feasible and has good economic benefits, providing a technical means for low-cost and rapid judgment of the water production interval of horizontal wells in low-permeability oil reservoirs.