Pages: 333 - 343
Abstract: The work describes and compares the methods for determination of the carbonate content in fifteen samples of Sarmatian–Badenian sandstones, which are reservoir rocks for natural gas in the central part of the Carpathian Foredeep in Poland. Typical sandstone samples were taken from a depth of 1600–2000 m.b.s. (metres below the surface) from drilling cores from well W-1 located about 4 km south of Sędziszów Małopolski, for the development and testing of a new technique for determining the carbonate content. Sandstones are composed of mainly quartz (up to 82 %), then carbonates (calcite and dolomite), feldspar, micas, rarely glauconite and pyrite. The carbonate content of reservoirs is very important for making decisions regarding to intensification of gas production by acid treatment of a near-wellbore region of sandstone. The carbonate content in the tested samples was determined using Scheibler’s volumetric method, petrographic modal data and ATR FT-IR spectroscopy (Attenuated Total Reflectance Fourier Transformation-Infrared Spectroscopy). According to the volumetric and petrographic analyses, the average carbonate content in the tested sandstones was 14.57 and 20.50 vol. %. The similar value 14.51 % (standard deviation in comparison to other methodologies is 0.59–7.75 %) has been obtained by simple and fast ATR FT-IR spectroscopy based on integration of the band coming from out-of-plane bending vibration of the CO32− group (ν2) about 870 cm−1. A comparison of obtained data showed that the ATR FT-IR procedure has the potential to be routinely used for determination of the carbonate content in sandstone samples.
Keywords: carbonate, Miocene sandstone, reservoir rock, natural gas, ATR FT-IR methodDownload PDF document