Accurate water saturation estimation in thin carbonate reservoirs is one of the major formation evaluation challenges in horizontal wells. This is mainly due to the strong shoulder bed effect of thick dense sections on the resistivity logs recorded in thin porous reservoir layers, particularly in horizontal wells.The performed work implies correction of the high resistivity log data acquired while drilling horizontal well sections by means of resistivity modeling. This has been achieved by building a forward model for the resistivity data acquired in the deviated section of the overlying reservoirs in water injector wells, where the porous section is thick and the shoulder bed effect is minimal. The resistivity model construction is based on the relationship of the deep and shallow Laterolog resistivity to the neutron porosity log responses measured in the thick reservoir sections. The established model equations are used to construct deep and shallow resistivity logs in the horizontal sections of thin reservoirs by resistivity inversion using the neutron porosity log data.Several well data sets have been tested and the results were complimented by test data, formation tester fluid sample analysis, Dean Stark measurements and core data. The results obtained confirmed that the resistivity inversion technique is applicable to compute water saturation in both the flushed zone (Sxo) and the un-invaded zone (Sw) for horizontal well sections drilled across carbonate reservoirs. The application of the inversion process allows generating resistivity log responses corrected for the tight shoulder bed effects, and providing more accurate water saturation estimation.
Abu Dhabi's mature field with more than 50 years of production history and over 350 wells that is presented in this paper is one of the world's largest offshore oil fields. As oil fields mature, water and gas breakthroughs become increasingly frequent and the understanding of fluid movement becomes crucial for proper reservoir management, efficient remedial works and optimum workovers and future wells drilling, which all expected to enhance oil recovery. This paper introduces an innovative logging technique designed to track fluid movement deep in the formation in flow and no-flow intervals and through casing.
The objective of this case study is to show the value of the NMR real-time log data, acquired while drilling, for reservoir characterization as a lithology independent porosity logging solution and most important for permeability computation. The applied methods are being discussed with much focus on the added value of the transverse relaxation time T2 spectrum analysis in a highly heterogeneous, upper Jurassic carbonate reservoir, to characterize the pore size distribution while geosteering the wellbore to track the better quality pore systems and generate a real-time permeability profile, supporting the later advanced completion run for the first time, in this offshore field. The current field development plans are based on drilling multi-lateral horizontal and highly deviated wellbores along the layers of Reservoir-D to enhance the injection and production efficiency. Running radioactive-based porosity logging tools with such complicated well trajectories poses a high operational risks and collide with environmental regulations, this paper presents a case where nuclear magnetic resonance (NMR) as a source-less porosity logging device, run with the conventional resistivity-gamma ray logging while drilling combination achieved effective real-time formation evaluation and supported efficient well placement to maximize the reservoir contact. The NMR formation evaluation supported the design of the following Inflow Control Device (ICD) well completion operation for water injection, in a timely effective process, later validated with production logging data. The application is focused on maximizing the value of the real-time LWD (NMR) data for the time-critical (ICD) design and deployment in the highly deviated/ horizontal drains drilled, offshore Abu Dhabi.
Sourceless porosity estimation has become more attractive because of evolving government regulatory and HSE requirements. The use of wireline nuclear sensors and their HSE procedures have a 50-year history, while nuclear sensors for logging while drilling share the last 20 of those years. Recently, the potential of using non-nuclear methods for porosity estimation has been explored in an offshore Abu Dhabi carbonate sequence. This paper presents a case study of nuclear magnetic resonance (NMR) logs while drilling, in comparison to conventional density and neutron logs using radioactive chemical sources. NMR T1 porosities were also compared to laboratory core results. Two approaches are investigated: Estimated hydrogen-index correction to NMR moveable-fluid volume using core-normalized porosities.An insight into an integrated NMR-acoustic approach, using the two sensor measurements to derive a corrected porosity. A workflow is proposed for optimized job planning, operational procedures, data-acquisition parameters, and interpretation techniques. Permeability estimation with NMR is discussed, and a selection of methods are considered and contrasted to laboratory core permeability and wireline formation-tester results. This paper explores the potential for sourceless porosity measurements through NMR and acoustic/NMR measurements in an offshore Abu Dhabi carbonate sequence in compliance with the HSE standards and government regulations, where the need for reconsidering reservoir characterization through sourceless porosity options will continue to grow.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.