The paper describes the procedures for planning, implementation, interpretation of diagnostic fracture injection test (DFIT), analysis of calibration tests (substitution, mini-frac) in hydraulic fracturing. The main stages of the procedures, recommendations, as well as the results are given. The advantages of injection tests over traditional methods of wells hydrodynamic studies in respect of low-permeability reservoirs are considered. Particular attention is paid to description of injection test results interpretation algorithm. Theoretical foundations of methods for injection tests analysis (i.e., before closure analysis, after closure analysis (Nolte method) and log-log analysis) are discussed. The main problem is the lack of reliable information about the geometry of the crack, its height and the pay zone of the fractured formation. These parameters are important for reliable assessment of reservoir permeability.
The article describes in detail the injection tests results interpretation technology. It is shown that the basis of a reliable interpretation is the simulation of hydraulic fracture created while performing the injection test. In the concluding section, we present approbation results of discharge tests interpretation technology performed for the wells of the Rosneft Oil Company. Good agreement between the values of permeability and reservoir pressure obtained by different methods indicates the equivalence of the analysis methods used. In addition, comparison of the results of the analysis with the data obtained from the Decline Analysis confirms their reliability and correctness of the approach adopted.
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