Oilfield Water Geochemistry as an Analogue Tool to Track the Provenance, Migration and Accumulation of Hydrocarbons in Petroleum Systems
Globally, about three barrels of water are produced for every barrel of oil, with water cut reaching 95% or more in mature fields. Costly industrial processes and water-specific technologies are required to manage and minimize the impact of oilfield water production. The development and implementation of innovative geochemical technologies are aimed to predict and alleviate production-related costs in water management. The automated characterization and classification of produced water can significantly reduce drilling costs and improve exploration opportunities by avoiding dry holes. Based on geochemical fingerprints, oilfield water research offers solutions for exploration and production (E&P) that can be used to track the provenance, migration and accumulation of hydrocarbons. Hydrochemical and multi-isotopic fingerprinting techniques are developed and applied for production allocation and for assessing fluid continuity and reservoir compartmentalization, especially to trace groundwater (and indirectly hydrocarbon) migration pathways, and to evaluate the impact of structural features on flow dynamics. As a novel exploration tool, hydraulic traps (created by the convergence of continental gravity flow and marine compaction flow of formation water) are traced to detect petroleum accumulations. The Iodine-129 method represents a special isotopic technique applicable to track the fate of organic matter. Due to the biophillic affinity of iodine, 129I-fluid ages from the inorganic phase can be correlated with depositional ages to define ascending or descending fluid migration from organic sources to host rock. Reserves estimates can be optimized by a log-independent quantification of physical parameters, especially by using representative salinity values in formation water to calculate water resistivity (Sw). Different Sw values may equate to considerable differences in the original oil in place (OOIP) or original gas in place (OGIP) volumes. For hydraulic fracturing, geochemical tools are essential to calculate recovery rates of fracturing fluids, to define nature and provenance of flowback water, and to provide evidence for the functionality and efficiency of natural or hydraulic fractures on gas mobilization. Heterogeneities in reservoir quality can be estimated ahead of the drill bit by numerical simulations of geochemical water-rock interaction processes. This work will provide an overview of classic and novel geochemical techniques for the fingerprinting of contaminant fluids, quantifying the provenance and recovery rates of flowback water through hydraulic fracturing, and tracing reservoir compartmentalization by groundwater migration and fluid reactivity.
AAPG Datapages/Search and Discovery Article #90337 ©2019 AAPG Middle East Region GTW, Regional Variations in Charge Systems and the Impact on Hydrocarbon Fluid Properties in Exploration, Dubai, UAE, February 11-13, 2019