Study of finely divided sludge effect on drilling fluids properties while drilling with complexes with detachable core receiver at Talnakhskoe deposit

Relevance of the research is caused by the necessity to study the effect of finely divided sludge on properties of drilling fluids while drilling with complexes with detachable core receiver at Talnakhskoe deposit. When drilling the exploration wells with the complexes with wireline at 1000 m of sinking from 7 to 8 tons of rocks are drilled out at the average. The main aim of the research is to study the effect of finely divided sludge, entering the drilling fluid, while boring with complexes with detachable core receiver on clay rocks and ore zone at Talnakhskoe deposit, on drilling fluid properties. The methods used in the study: methods of X-ray fluorescence spectrometry, electron microscopy, X-ray, tomography and spectroscopic analysis to determine the mineral composition of argillaceous rocks; determination of particle size distribution of drilling fluid sludge (hereinafter - the sludge); determination of zeta potential and the Debye radius; methods described in ISO 10414-1 and ISO 13503-1. The results. The study of fractional composition of solutions with finely divided sludge allowed establishing particle size distribution in drill cuttings. The dispersion clay particles can be divided according to the degree of the colloidal activity into: very active 0,46…0,69 mμm in size; active 1,10…3,32 mμm in size; less active ranging in size from 5,46…10,28 mμm; non-colloidal active with dimensions 10,28…43,04 mμm. The geometric mean size of particles in finely dispersed phase solutions ranges from 1,856 to 1,931 mμm. Bringing of active and inactive particles in a solution is a natural way to create solutions with the dispersed solid phase, which form a «clay» crust on the borehole wall with a pressure drop and provide rock colmatation. Experience in constructing a well of more than 1,500 m on the Talnakh deposits confirms the appropriateness of applying the finely divided phase in drilling fluid composition to bore deep wells with complexes with detachable core receiver.