New Gas Tracer Convection–Diffusion Model between Wells in Heavy Oil Reservoirs

Abstract

Different from conventional oil and gas, the storage and seepage space of heavy oil reservoirs are extremely complicated, thereby making it difficult to describe reservoirs in detail over the heavy oil production process. Acquiring development results accurately in real time is still a demanding task, and it is also a challenge to predict the average remaining heavy oil saturation during the production process. Tracers are mostly used to monitor steam flooding to obtain the real-time dynamics during heavy oil production in fields. However, the flow pattern of gas tracers in heavy oil is still unclear, with very rare investigations. In this work, a new one-dimensional gas tracer convection–diffusion model that considered the retention and oil phase migration velocity was established using the percolation law of gas tracers. The reservoir description coefficient f was introduced to describe the relationship between the migration velocities of the oil and gas phases in the heavy oil reservoir. Subsequently, a new gas tracer well pattern flow model was also constructed based on the gas tracer linear flow model and verified simultaneously. The results revealed that at a larger partition coefficient, more amounts of gas tracers were distributed in the crude oil, the duration of stagnation was extended, and the start time of tracer production was moved backward. The injection velocity had a very minor effect on the tracer production performance. As the fluid injection rate increased, the duration of gas tracer production was extended; however, after the injection rate reached a certain level, the difference in the arrival time of the peak become minor. The effects of crude oil viscosity on the tracer production were reflected by the breakthrough time, production time, peak concentration, and peak arrival time of the tracer. Compared with the production curve of the crude oil viscosity, the peak of the production curve with high crude oil viscosity has a faster peak time and a large peak value. The reservoir description coefficient mainly affects the peak concentration of tracer production and has very minor effects on the production time and other parameters. The outcomes of this work can be applied in the field of heavy oil development, in particular, for the heavy oil reservoir description and dynamic monitoring.

Design, synthesis and performance of novel fluorescent polymer microspheres tracers based on aggregation induced emission

“…The fluorescent polymer microspheres tracers prepared as 0.2 mg/L fracturing fluid suspension and heated at different temperatures (25,50,80,110, and 140 C) for 1 h, then the fluorescence emission spectra of the mixture were tested after it cooled down to room temperature. The pH of the aqueous solution was adjusted by sodium hydroxide and hydrochloric acid, and then a 0.2 mg/mL suspension of the fluorescent polymer microspheres was prepared to test the fluorescence emission spectra at different pH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). The suspension of fluorescent polymer microspheres was also left under natural conditions for 30 days and their fluorescence emission spectra were S C H E M E 1 Synthesis route of fluorescent microspheres tested every 5 days.…”

“…[7][8][9] The tracers can return the underground situation to the ground through signals, which can better assist in the field survey of oil reservoirs (including inter-well connections, inter-layer connections and heterogeneity). [10][11][12] Many tracers have been used in dynamic monitoring, evaluation of oilfield production, 13,14 improving recovery measures and so on.…”

Study on Interpretation Method of Multistage Fracture Tracer Flowback Curve in Tight Oil Reservoirs

“…Due to the infiltration of tracers in different fracture systems after fracturing, the resulting tracer flowback curves can vary. Therefore, analyzing tracer flowback curves allows for the determination of postfracturing fracture morphology and the acquisition of relevant fracture parameters. − This method can also be utilized to evaluate different fracturing parameters and guide reservoir assessment, geological design (design of an oil field development plan), fracturing design, and workflow design. , The tracer flowback curve is a tool used to study the flow pathways of fluids in underground reservoirs. When tracers are injected into the reservoir, they move along with the fluid flow.…”

A Rotated Similarity Reduction Approach with Half-Sweep Successive Over-Relaxation Iteration for Solving Two-Dimensional Unsteady Convection-Diffusion Problems

“…Meanwhile, standard approaches become unstable when convection dominates, and unique techniques are required to numerically approximate solutions. CDE appears in various applications of science and engineering such as gas transport [1][2][3], rotating disks [4][5][6], water pollution [7,8], and porous media [9][10][11]. Owing to CDE's wide applications, it has attracted Iteration for Solving Two-Dimensional Unsteady Convection-Diffusion Problems significant attention and interest from mathematicians and researchers in recent years.…”