Abstract

The purpose of this paper is to demonstrate the value of field deployable surface logging technologies when high quality surface data is modelled against high-end laboratory and downhole petrophysical logs. Modelled surface data responses utilized on subsequent wells of a multi-well campaign, will eliminate the need to transport rock or core samples to labs, or run high-cost downhole logs. In turn, eliminating "lost in hole" risks and expensive sample collection, storage and transportation needs, which result in reducing associated costs and related carbon emissions. In addition to these direct implications, there are ancillary benefits such as the lower carbon footprint in manufacturing surface logging equipment.

This work tries to understand the challenges posed by the sub-surface complexities and attempts to find answers through physical evidence; utilizing risk-free surface data acquired during drilling and data gathered through organic and inorganic laboratory measurements. Formation evaluation challenges in highly fractured, stacked reservoirs with multiple source rocks and structural complexities which have complicated charging histories, are common in the Middle East. Finding additional pay zones, understanding the contribution of individual oils to the overall production, or evaluating the compartmentalization within the reservoir by resolving the heterogeneity of the reservoir rocks, are to name but a few. Formation evaluation challenges are mostly attributed to formation heterogeneity, which we have aimed to address through the integration of petrophysical and geochemical data within this work.

Within this project maturity, richness and other character interpretations elaborated from the geochemical data will be combined with important petrophysical properties of the carbonate intervals to predict reservoir heterogeneities. These interpretations could support perforation interval selection on subsequent wells in the field through the understanding of the mobility of the oils, and ultimately impact on production strategies. The analysis has the objectives of establishing results to support completion decisions through understanding reservoir quality and reservoir fluid heterogeneities specific to the basin studied and the petroleum system in place. The petrophysical reservoir properties such as hydrocarbons in-place, mobility of the oils, porosity, permeability, fracture intensity, and fluid quality assessment in the reservoir will be tied into geochemical analyses to this extent.

The reservoir properties determination pursued in this study has been carried out using a number of integrated analytical techniques on DST oil samples of six offset wells and rock cuttings, as well as petrophysical logs and advanced mud gas data. The concepts, tools and methods that have been demonstrated for evaluating crude oils, natural gases and petrophysical characteristics of the rocks are applicable to many problems in petroleum production and field development, as well as exploration efforts, and are largely recognized to help reducing the associated uncertainties in a cost-effective manner.

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