PERTAMINA EP's Niru field development objective is to drain attic oil from the X0 sandstones. The thin fluvial-distributary channel environment of the reservoir brings drilling challenges due to the complex reservoir geometry and uncertain lateral continuity. A horizontal well was planned in order to maximize recovery of oil in this mature oil field well.An integrated LWD solution combining fit for purpose real time measurements from a continuous rotating bottom hole assembly, bed boundary mapping tool, formation images with real time correlation and Geosteering software, was used to steer the well in real time. The real time monitoring of petrophysical parameters, enabled TD to be decided after achieving maximum exposure to the reservoir. In addition, the analysis of dip information from formation images acquired while drilling enabled an important update to the field geological model to be made, while highlighting the limitations in reservoir characterisation of using data from vertical wells drilled into a structure with lateral variationsThe improved understanding of the reservoir, as well as the capabilities of the deep directional resistivity tool to locate and map the roof of the reservoir while drilling, enabled the wellbore to be maintained 1-2 m below it.This precise and accurate positioning of the wellbore in the reservoir sweet spot, resulted in the sustained production of oil at a rate almost 4 times higher than expected with the addition of low water cut. 2 IADC/SPE 155056The benefits of real time bed boundary mapping and well placement techniques have led to both a better understanding of the X0 channel sandstones reservoir, and a direct change in the development strategy of the field by Pertamina EP. This will now include further horizontal wells, which are now considered to be essential to the successful development of the Niru field, for draining oil from the thin (2-4 m thick) reservoir, which was previously thought to be impossible.
The presence of shale in thin beds reservoirs affects formation evaluation where the standard conventional log analyses are not designed to properly correct this effect. The conventional logging tools, with low vertical resolution, are not able to characterize these thin beds. This implies that log values do not represent the true bed or layer properties, but rather an average of multiple beds. Muda Formation are characterized by thin bed layers, made up of clastic rock sequences with dominant lithology of sandstone inter-bedded with shale, siltstone, and organic material as confirmed by drilling cuttings, logs response, and also supported by observation from sidewall cores. There are many uncertainties related to the presence of thin beds, primarily sand, silt, shale or their combination in term of their petrophysical properties and lateral extent. Inadequate reservoir characterization can cause significant amounts of oil and gas to remain unidentified. Accurate petrophysical parameters determination play an important role in the development plan of a field. The lateral and vertical variations in the petrophysical properties of the reservoir lead to different scenarios of the field development. The study of Muda Formation in this structure has integrated the sidewall core and log data. The contribution of the thin sand laminae to the average log response resulted in underestimating the porosity (Ф) and hydrocarbon saturation (Sh). The advanced measurement, like the resistivity anisotropy, proved quite useful as the vertical and horizontal resistivity across these beds leading to measurable electrical anisotropy. The resistivity measured perpendicular to the bedding is significantly higher than resistivity measured parallel to the bedding. The situation occurs due to high resistivity sand layers interbedded with low resistivity shale layers. The true sand porosity and hydrocarbon saturation were calculated using the laminated sand shale sequence and calibrated with core data. The study led to the more realistic petrophysical estimation of the sand shale laminae. A combination and integration of high-resolution image log for sand count, nuclear magnetic resonance (NMR) for porosity evaluation and triaxial resistivity for volumetric model through Laminated Sand Analysis approach are found useful to solve thin bed reservoir issue.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.