<p>The authors have presented results on development of a mathematical model of convective evolution of a tracer marker in natural reservoirs with a hydrofracturing crack with allowance for the leaks from the crack into the stratum. To construct the pressure field as applied to two-dimensional problems, a quasi-stationary method has been developed that uses the idea of successive change of steady states. To find the dimensions of the zone of pressure perturbations in a porous medium, that is formed by the injection of the tracer into the crack, use has been made of the law of conservation of mass. Dependences have been established of the velocity of motion of the tracer marker in the hydraulic-fracturing crack and the surrounding porous medium on the parameters of the stratum and the well.</p><p>Dependences have been constructed of the front and back boundaries and the length of the marker in the crack and the surrounding porous medium on the reservoir parameters of the stratum and time. Formulas have been determined to compute space–time concentration distributions of the tracer in the stratum with a crack. On the basis of an analysis of the theory, regularities have been established of the formation of satellite markers generated by tracer motion in the crack. It has been shown that in low-permeability reservoirs, the length of the satellite marker is much smaller than its dimensions in the crack.</p>