PETROPHYSICS AND ROCK PHYSICS CORRELATION ANALYSIS IN DETERMINING FORMATION PROPERTIES ON SHALY SANDS FORMATION

摘要

Rocks cutting samples of the Barakuda well showrnthat the developing reservoir around the area isrnsandstone. The Barakuda well is an exploration wellrnlocated in the Tarakan basin. The low-resistivityrnphenomena that occur in the reservoir intervalrnindicate that the sandstone reservoir on this locationrnis a heterogeneous sandstone. This means all rocksrnin the interval, including dirty sands, can bernconstructed by mixing clean sand and shale. Thisrnkind of case has a significant effect in petrophysicsrnparameters if evaluated without considering thernheterogenity. For example, the porosity andrnhydrocarbon saturation values would bernunderestimated if we assume the reservoir rocks arernhomogenous. Thus, we need to determine thernreservoir sand types to evaluate the petrophysicsrnparameters in the most compatible way.rnIn this research, the heterogenity of the sandstonernwas analyzed using a correlation between thernThomas–Stieber (TS) and Yin–Marion (YM)rnmodels as petrophysics and rock physics analysis.rnThese analyses are used to determine sand types inrnthe reservoir interval. The TS model predicts thernporosity resulting from various modes of sand-shalernmixing. The YM model predicts the associated Pwavernvelocities. Together, they offer a higherrndegree of constraint of formation properties.rnThe results show that from eight zones reservoirrnrocks, the first five zones are laminar shale and thernlast three are dispersed shale. Both these modelsrnhad the same conclusion in determining sandstonerntypes.