Baskoro, Anindito (2022-12). Source Rock Reconstruction and Hydrocarbon Mass Balance Assessment - Applied to the Wolfcamp Formation in the Permian Delaware Basin. Doctoral Dissertation.
Thesis
Improved efficiency of hydrocarbon resources exploration is directly linked to an accurate petroleum system analysis, including detailed quantification of hydrocarbon (HC) masses involved in a basin from generation to production. The quantified HC masses must be balanced following the fundamental laws of mass conservation. This is particularly important for a basin with unconventional-conventional petroleum systems where the generated HCs from the source rock are either expelled out from or retained within the source rock. Expulsion efficiency becomes even more critical as it largely determines the HCs in place, both for the source rock or out of the source rock accumulations. Before performing the hydrocarbon mass balance calculation, basin-wide source rock (initial quality and quantity and litho- and organo- facies) is reconstructed following the proposed workflow. The workflow is applied to Wolfcamp Formation in the Permian Delaware Basin as it is an excellent example of unconventional-conventional petroleum systems. Firstly, the proposed kinetic-based inversion workflow results show a considerable range of restored initial hydrogen index, ca. 188-594 mgHC/gTOC, and total organic carbon, ca. 1.49-3.17 wt%, values indicating source rock heterogeneity of the Wolfcamp. The workflow restores the measured HI and TOC significantly as Wolfcamp is within the oil to gas generation (transformation ratio ca. 56-84 %) window but initially has a good to excellent source rock potential. Secondly, seven basin-wide lithofacies are identified within the Wolfcamp Play by applying unsupervised machine learning workflows on well-log measurements. Wolfcamp source rock basinal lithofacies is identified as organic-rich siliceous mudstone with marine clastic organofacies dominated to mixed argillaceous mudstone with mixed marine-terrigenous organofacies dominated, interbedded with siltstone and limestone, reflecting a shallow-to-deeper marine to deep marine depositional environments. Finally, the restored source rock property and identified basinal facies are integrated to the 3D Delaware basin model to calculate the generated HC. The calculated generated HC volumes (p90/50/10) are 705/1,332/3,016 Billion Barrels of Oil Equivalent (BBOE). Ultimately, the proposed workflow assesses the mass balance and estimates the mean remaining recoverable hydrocarbon of 33/65/149 BBOE with mean overall expulsion efficiency of 50%, which may be used as a reference in modeling unconventional interbedded play.
