SPWLA HAHZ SIG 2026 Workshop 2
About
Welcome to SPWLA HAHZ SIG's Workshop for 2026.THIS EVENT IS A VIRTUAL EVENT, ATTENDANCE WILL BE VIA TEAMS MEETING
WORKSHOP 2 will be hosted online to correspond with Americas Time Zone.
Thursday 16th April, 10am Houston, 5pm Paris, 7pm Dubai, 11pm Singapore
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WORKSHOP 2 PRESENTERS:
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Parvez Butt, No Hidden Pay - Constrained LWD Resistivity Modeling for Improved Formation Evaluation of Horizontal Water Injectors
Harald Bolt, Depth Solutions - Quantification, and Value Impact, of Vertical Depth Uncertainty in HaHz wells
Mike Bower, SLB - The Industry's Need for a True Triaxial, Colocated Multi-Depth Azimuthal Resistivity in LWD: The Step Change to Increased Sensitivity and Certainty
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ABSTRACTS:
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Constrained LWD Resistivity Modeling for Improved Formation Evaluation of Horizontal Water Injectors
Parvez Butt, No Hidden Pay
Permeability is a fundamental petrophysical attribute required to accurately evaluate recoverable reserves and design an appropriate field-development strategy. Because logging tools do not measure absolute permeability, minimizing uncertainty in the evaluation of log-derived permeabilities remains one of the most critical petrophysical challenges in the oil industry. Horizontal development in laterally heterogeneous carbonate reservoirs also requires evaluation of lateral permeability variations to optimize completion design while maximizing reservoir exposure via precise well placement in real time. This paper demonstrates innovative methods to evaluate lateral permeability variations in heterogeneous carbonate reservoirs.
The workflow for log-derived permeability predictions is based on empirical relationships using nuclear magnetic resonance (NMR) and high-resolution imaging tool measurements. These are normalized in an integrated multidisciplinary approach using core, well test, production logs, and formation-tester mobility data where available. Traditionally, formation-tester tools have been used to obtain single-pressure and mobility values at each test station. The logging-while-drilling (LWD) formation tester can be oriented azimuthally to help evaluate permeability anisotropy, which is a key factor for reservoir characterization in laterally heterogeneous reservoir layers. The oriented data can also be used to adjust the well plan in real time to maximize reservoir exposure in the desired “sweet spot.”
Variations in the oriented LWD formation-tester measurements at each depth station exhibited favorable correlations to azimuthal changes observed in the LWD high-resolution microresistivity image. Detailed image analysis further helped to understand the mechanism that governs the azimuthal permeability profile. The combination of oriented LWD formation-tester and highresolution image data also aided in making better realtime geosteering decisions, as well as in the planning and design of a future field-development program within the local reservoir sector. Operational considerations to maximize data quality rely on an optimized bottomhole assembly (BHA) design, accurate depth control, and robust orientation techniques based on best practices and lessons learned.
This paper presents an integrated approach for well placement and an improved understanding of flowunit characterization via the first-time use of oriented formation-tester data in conjunction with corresponding high-resolution images in a laterally heterogeneous reservoir.
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Quantification, and Value Impact, of Vertical Depth Uncertainty in HaHz wells
Harald Bolt, Depth Solutions
Uncertainty in subsurface models arises from both the accuracy of acquired data and the calculation methods employed. Subsurface well positioning and associated positional uncertainty are key to describing well geometry and the localization of geologies, reservoirs, fluid interfaces, and other geological events (faults, seals, gradients), through to hydrocarbon initially in place (HCIIP) estimation. These uncertainties directly affect HCIIP, which underpins critical economic decisions about subsurface prospect viability. Key input parameters—including gross reservoir volume, sand count, porosity, fluid saturation, and conversion factors—are derived from seismic interpretation, wellbore measurements, petrophysical evaluation, and fluid characterization.
Traditionally, Vertical depth, and hence volumetric, uncertainty has been characterized industry‑standard ISCWSA recommended and similar type approaches. Particularly in high‑angle and horizontal (HaHz) wells, and especially where targets require very high levels of precision, relying solely on measured depth (MD) the resulting positional variances can be significant. Without explicit management of positional uncertainty expectations and requirements, this can lead to effectively unbounded uncertainty.
The workshop presentation introduces relational navigation that makes use of along-hole depth (AHD) and 3D Way-point, a rigorous framework for quantifying subsurface 3D positional uncertainty. Relational navigation is an advanced, yet conceptually straightforward, tool that allows position and positional uncertainty to be calculated and reported in intuitive terms. It improves the fidelity of reported results and, critically, provides an explicit link between technical accuracy specifications and economic value assessments. This is applied in an example North Sea HaHz wel.
The presentation scrutinizes the contributory influence of each parameter within the standard HCIIP equation, including specifically Vertical depth, aiming to optimize well survey design whilst taking a balanced approach to accuracy specifications. By controlling Vertical depth uncertainty to meet specified tolerances, operators can increase recoverable reserves and make more robust business decisions (Fig. 2). The differences between the relational navigation approach and currently used industry standard (ISCWSA) methods is highlighted.
The example demonstrates how applying relational navigation results in both enhanced value of HCIIP calculations as well as creation of greater stakeholder confidence in reserves estimation. This clearly highlights the tangible improvements in HCIIP value achieved through improved management of Vertical depth uncertainty, this specifically in HaHz wells.
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The Industry's Need for a True Triaxial, Colocated Multi-Depth Azimuthal Resistivity in LWD: The Step Change to Increased Sensitivity and Certainty
Mike Bower, SLB
Multi-Depth Azimuthal Resistivity (MDAR) system represents a significant advancement in logging-whiledrilling (LWD) technology. By leveraging colocated, calibrated triaxial EM measurements across multiple depths/frequencies, the MDAR architecture addresses key limitations of conventional deep and ultra-deep azimuthal resistivity tools that rely on tilted, noncolocated antennas. This innovative design improves measurement accuracy, reduces systematic errors, and enhances signal-to-noise ratio, enabling more reliable inversion results.
The MDAR system offers a range of critical benefits that collectively enhance drilling and reservoir characterization. By providing high-fidelity measurements with reduced uncertainty, it enables more confident geosteering decisions and improved correlation with seismic data. Its enhanced look-ahead capability, achieved through lower firing frequencies, multiple spacings closer to the bit, and colocated antennas, allows earlier detection of formation boundaries and anisotropy even in complex geological settings. Transmitter-referenced inversion workflows, combined with shallow and medium array measurements near the bit, significantly reduce the time between data acquisition and inversion, here introduced as inversion time to bit, and actionable insights, here introduced as time to decision execution, without compromising quality. Additionally, the system’s sensitivity to borehole parameters supports inversion-based workflows that correct borehole effects, ensuring accurate petrophysical interpretation. Finally, full triaxial tensor measurements unlock advanced complex resistivity anisotropy inversion techniques, including true dip azimuth determination and deterministic uncertainty quantification, expanding the range of answer products available to operators.
Field trials in challenging formations have verified that the MDAR platform consistently adds a next level performance over existing tilted and transverse antenna DAR and UDAR platforms in terms of depth of detection and vertical resolution, quality of inverted outputs, and operational efficiency. These results confirm that MDAR is a step change in LWD resistivity technology, paving the way for improved reservoir characterization and optimized drilling performance for look-ahead and look-around applications.
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