NMR-relaxometry laboratory study of fluids taken from boreholes

Abstract

The relevance. Timely diagnostics of the fluid, taken from a borehole, allows determining the rise of flooding and destruction of the bottom-hole zone at the initial stage of well operation. Now diagnostics of a liquid phase is carried out by means of hydrochemical analysis of water samples in laboratory conditions. This method provides meaningful data on ionic-salt and microcomponent composition of the studied liquid. Diagnostics operativeness is very important in the most of cases, that is why it is important to find alternative methods and approaches for reservoir fluids express studying. This method is NMR-relaxometry. It allows typifying effectively the fluid taken from a borehole in combination with the hydrochemical data. The aim of the research is to develop the NMR-relaxometry method as applied to diagnostics of the fluid taken from a borehole, based on the dependence of transverse relaxation time on concentration of paramagnetic ions. The methods used: expanded hydrochemical analysis including the determination of ion-salt and microcomponent composition and laboratory methods of pulsed NMR-relaxometry aimed at determining transverse relaxation time. The results. Using the laboratory hydrochemical analysis data on ionic-salt and microcomponent composition of the fluid taken from a borehole and based on the conducted NMR-investigations, the authors have experimentally confirmed the considerable dependence of transverse relaxation time on change in concentration of paramagnetic metal ions. The authors determined the dependence of the transverse relaxation time on the content of calcium and sodium ions. The latter provide a basis for distinguishing technogeneous and formation water, subsequent to the results of hydrochemical analysis, which is the basis for prompt typification of the fluid taken from a borehole by NMR-data. This dependence allows distinguishing exactly the technogeneous water characterizing by high content of metal paramagnetic ions