Doctor of Philosophy (PhD)
This research explores the characterization of petrophysical parameters such as cementation exponent, saturation exponent and effective porosity as a function of cations exchange capacity (CEC), and its impact on shaly sand interpretation. Experimental and field data were used in the study. The latest LSU model for shaly sand interpretation uses of two cementation exponents, mf and mc, to represent the tortuosity of electric current path in free water and clay bound water, respectively. Experimental measurements on three types of rock, clean sand, shaly sand and pure shale using different brine salinity, were conducted to validate the use of these two cementation exponents. The results showed that using two cementation exponents determined from representative clean sand and pure shale to characterized electrical behavior in shaly sand are substantially better than using just one cementation exponent determined from shaly sand itself. Using the same experimental results a correlation between saturation exponent value (n) and CEC as a function of brine salinity was also developed. Also a brine salinity of 15,000 ppm was found to be upper limit of “low” salinity range in which extra care is needed for shaly sand evaluation. Monte Carlo simulation was used to evaluate the uncertainty of water saturation calculation using LSU model with two cases: correlated input variables (formation conductivity and total porosity) and uncorrelated input variables (independent). Least square linear regression method was also used to evaluate the most significant input parameters in LSU model. This study also introduces a new simultaneous method of calculating effective porosity and cations exchange capacity (Qv) of liquid-filled reservoirs using gamma-ray, density and neutron tool responses. This method isolates the effect caused by the actual clay mineral from those of clay-sized particles in the formation. Further more, this effective porosity calculation also takes into account dry clay properties. The application of the modified LSU model in the evaluation of thinly-bedded shaly sand reservoirs is possible whenever the required criteria are met. The result was the identification of additional hydrocarbon potentials.
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Kurniawan, Fnu, "Shaly sand interpretation using CEC-dependent petrophysical parameters" (2005). LSU Doctoral Dissertations. 2384.