Influence of drilling mud and subsequent treatment by acid and acid-demulsifier solutions on permeability of sandstone reservoirs

UDK: 622.244.442.063

DOI: 10.24887/0028-2448-2017-5-12-16

Key words: drilling mud, acid mixture, permeability build-up

Authors: M.Yu. Zubkov, A.G. Potapov, Sh.Sh. Ilyasov, E.G. Mamedov (West-Siberian Geological Centre LLC, RF, Tyumen)

The article presents results of experiments on models of filtration аcross sand and silt deposits of Low Cretaceous age of one of the fields in Western Siberia. Models were treated by drilling mud and subsequent by different acid mixtures to restore their permeability. We observed fall-off in permeability of granular reservoir in the result of drilling fluid (mud) pumping. Partial removal of mud cake formed under the action of the differential pressure on it from the ‘reservoir’ of about 7 MPa led to restoration of the permeability of a reservoir model only 18-21 % of their original permeability. Using post-processing reservoir model by acid mixture allowed to increase model permeability to 36-37% of its initial permeability and demulsification - up to 50-58%. The results can be used in the secondary formation exposing granular reservoir in order to increase their productivity. The effect of the mixtures used in the experiments is, firstly, in the chemical decomposition formed mud cake and, secondly, in the destruction of the water-hydrocarbon emulsion.