bluuebunny/crossref_metadata_2025_split huggingface dataset:
Internal Multiple Suppression Method and Its Application in Complex Buried Hill of Bohai Bay
Authors: Duan X. , Ding H. , Zhang J. , Ma Z. , Han Z. 
Published: February 2024

As the largest offshore oilfield in China, Bohai Oilfield has made good exploration discoveries in various target strata in the past decade, especially in the exploration of deep buried hills. Because the shallow favorable targets have been nearly drilled out, the exploration focus of Bohai oilfield is gradually shifting to the middle and deep layers. The buried hill have become the most important research hots pot of Bohai oilfield, and several large gas reservoirs have been discovered in Archean strata. The main reservoir type of buried hill oilfield is fracture, which has complicated characteristics with low porosity, strong heterogeneity and complex fracture distribution. The average depth of buried hill is about 4500m, so it is difficult to accurately predict and describe good fractured reservoir in the exploration and development.
Because of the deep buried depth, the quality of seismic data is usually very poor. On the one hand, the effective signal of fractured reservoirs are very weak, and the low S/N seismic data is hard to recognize fractured reservoir. On the other hand, there are a lot of residual internal multiples, and their amplitude is even stronger than the reflected wave of fractures. Taking the normal processing procedure into consideration, most of the multiples like surface-related multiples have been well suppressed during the seismic data processing. In order to clearly identify the real reflection wave of fractured reservoir, it is necessary to suppress the internal multiples and enhance the effective signals.
Generally, the methods of suppressing multiple waves are divided into two categories: one is the filtering method based on signal analysis and processing, such as t -p transform and f-k transform; the other is the prediction subtraction method based on wave equation, such as wave extrapolation method and inverse scattering series method. The first kind of methods have certain limitations: the dynamic correction speed of multiple waves and primary waves is similar, which weakens the effectiveness of t -p transformation, multiple and primary waves have similar slopes, which weakens the effectiveness of f-k filtering. The second type of method mainly uses the generation mechanism of multiple waves to predict and suppress multiple waves. It comprehensively considers the kinematic and dynamic characteristics of multiple wave propagation and can adapt to complex underground structure. It uses its own data as a multiple wave prediction operator, requires less or no assumptions about underground structure, and attenuates multiple waves without damaging the primary reflected signal. For internal multiple waves, the current effective method is the inverse scattering series method based on the point scattering model. This method does not need a prior velocity structure model, and has a good adaptability to complex structures, but the calculation is very large.
Breakthrough Solutions for Lost Circulation Control in Oilfield Drilling: Unleashing the Power of Biopolymer Modified Graphene and CaCO3 synergy
Authors: Ahmad Hafiz Mudaser , Kamal Muhammad Shahzad , Murtaza Mobeen , Nabbat Yousif Al , Arifi Sulaiman Al , Mahmoud Mohamed 
Published: February 2024

Abstract
Lost circulation is a common problem encountered during drilling operations, where drilling fluids escape from the wellbore into the surrounding geological formations, resulting in reduced drilling efficiency and increased costs. Conventional lost circulation materials (LCMs) like calcium carbonate (CaCO3), mica, ground walnut shells, fibrous materials, and cross-linking agents are usually added to drilling fluids to plug the lost circulation zone. Further, nanoparticles, such as graphene and carbon nanotubes, offer a new generation of solutions for controlling fluid loss into lost circulation zones. The particle size distribution of LCMs, their stability, and dispersion play a significant role in controlling losses. The combination of LCMs and nanoparticles can provide a synergistic effect for lost circulation control. In this study, a mix of biopolymer-modified graphene and CaCO3 is proposed as a potential solution for lost circulation control that combines the unique properties of biopolymer, graphene, and CaCO3. The potential of the novel solution was investigated by conducting rheology and fluid loss tests. Their synergistic effect was investigated by incorporating them in different concentrations in drilling fluid and the optimum concentration was chosen based on rheology and fluid loss results. Experimental observations revealed that the combination of biopolymer-modified graphene and CaCO3 resulted in the formation of a durable and impermeable mud cake on the wellbore wall, effectively bridging the lost circulation zone. This innovative approach significantly reduces fluid loss in comparison to the conventional use of CaCO3 alone. By filling the nanopores of the CaCO3 bridge, the modified graphene contributes to a robust and reliable lost circulation control solution. Moreover, the inclusion of modified graphene improves the rheological properties of the drilling fluid, facilitating easier pumping and enhancing its capacity to suspend CaCO3 and other weighting materials. The proposed solution is biodegradable, environmentally friendly, and can withstand HPHT conditions, making it a viable option for real drilling conditions.
Fracture Monitoring and Characterization Using Unsupervised Microseismic Data Analysis
Authors: Misra Siddharth , Chakravarty Aditya 
Published: February 2024

Abstract
The study shows the use of unsupervised manifold learning on microseismic data for fracture monitoring and characterization. Manifold learning condenses complex, high-dimensional data into more concise, lower-dimensional representations that encapsulate valuable underlying patterns and structures of the data. The study leverages Uniform Manifold Approximation and Projection (UMAP) methodology to efficiently convert high-dimensional data into a graph-based, lower-dimensional representation. This transformative approach adeptly captures meaningful patterns and structures while preserving both local and global distances; thereby, the topology. In this study, the unsupervised manifold learning is applied on accelerometer and hydrophone data obtained during an intermediate field-scale hydraulic stimulation experiment conducted at the Sanford Underground Research Facility in South Dakota to measure, monitor, and characterize fracture propagation in near-real-time. Each micro-earthquake location identified using travel-time information is assigned a fracture type using unsupervised manifold learning, and later is assigned a fracture-plane label using semi-supervised manifold learning. Our findings highlight the precision and accuracy of our proposed method in preserving fracture network clusters and fracture-plane labels using signals from both accelerometers and hydrophones. These remarkable results underscore the potential of the Uniform Manifold Approximation and Projection (UMAP) technique as a versatile unsupervised-learning tool for unveiling the intrinsic structural features embedded within microseismic signals generated during hydraulic fracturing for purposes of fracture monitoring and characterization.
Next, this study addresses the challenge of reliably assigning fracture-plane labels to microseismic events created during hydraulic stimulation. Most events lack clear labels due to scattering and uncertainty in event locations. To tackle this, the study introduces a semi-supervised learning strategy based on UMAP that utilizes a sparse dataset with pre-labeled fracture-plane categorizations. By combining event coordinates and Fourier spectra from geophone signals in a low-dimensional manifold, this approach achieves precision and recall rates exceeding 92% while using only about 20% of labeled events. This method remains robust even in the presence of location errors, making it valuable for enhancing fracture network characterization in various applications, including hydrocarbon and geothermal production.
Research and Application of Adaptive Ghost Wave Suppression Method in Time-Space Domain
Authors: Wang Yichuan , Ma Xugang , Liu Gongli 
Published: February 2024

Summary
Source ghost waves and cable ghost waves can generate frequency trapping effects, resulting in the loss of low-frequency and high-frequency information in seismic data, seriously affecting the imaging quality of seismic data, and increasing the difficulty of later seismic data interpretation and reservoir inversion. The ghost wave delay time can be expressed as a function of the depth of the detector. When the cable depth is accurate, the difference between the total wave field minus the primary wave field and the ghost wave energy should be minimized. Convert the automatic optimization problem of cable depth into a least squares problem, and obtain the true cable depth by solving the objective function. By scanning the depth of the cable and combining it with the matching subtraction algorithm, accurate cable depth can be obtained. Design an anti filter to effectively suppress ghost waves. By designing a single-layer reflection model for algorithm testing, the effectiveness of this method is verified. After removing ghost waves, the energy of the trap points has been greatly restored and improved, and the energy of the low-frequency and high-frequency ends of seismic data has been well improved. Adaptive ghost wave suppression technology can effectively suppress source ghost waves and cable ghost waves, achieving the goal of eliminating traps, expanding seismic frequency bands, and improving seismic data resolution. This method not only has good processing results in actual marine seismic data processing, but also has high processing efficiency and good applicability to seismic data. It can be well applied to conventional horizontal cable seismic data and oblique cable seismic data. Significant improvement in the quality of seismic data provides an important data foundation for reservoir research.
Cased Hole Reservoir Evaluation in Old Wells with Complex Completion and Lithology – A Case Study from a Mature Gas Field in the Dnieper-Donets Basin, Ukraine
Authors: Petrokushyn O. , Abliakimov L. , Kuznetsov V. 
Published: February 2024

Abstract
The Dnieper-Donets basin (DDb) is the biggest and most explored hydrocarbon region in Ukraine. The DDb is a Late Devonian rift, filled with pre- and syn-rift Devonian sequences and overlaid with post-rift Carboniferous, Permian, Mesozoic and Cenozoic fill. The depth of the basement is found at a depth of approximate 4–5 km in the northwestern part of the basin. However, it dips along its strike southeastward and lies below about 15 km near the Donbas foldbelt (Figure 1). DDb is also a salt basin. While in its axial part salt penetrates over 10 km thick Carboniferous-Permian sequence, this part of the basin accommodates the biggest known hydrocarbon field (Figure 2) (T. Petrovska et al., 2021).
The dominant reservoir lithologies that contain most of oil and gas reserves in DDb are clastic rocks. Lower Carboniferous-Lower Permian carbonates and fractured anhydrites near the top of Paleozoic sequence contain comparatively smaller quantities of hydrocarbons. Hydrocarbon accumulations in the DDb are primarily structural traps, however faults and stratigraphic pinchouts usually control outlines of individual pools. Majority of the hydrocarbon fields in Upper Carboniferous-Lower Permian reservoirs are in faulted anticlinal uplifts covered by Permian salt seal, while fields in Lower Carboniferous reservoir rocks are usually associated with salt-assisted structural traps in deep, central basin areas. The first hydrocarbon shows in DDb were first recorded in 1936. The industrial hydrocarbon extraction has begun in 1950s-1960s when several significant gas fields were discovered (Ulmishek, 2001). There are over 200 hydrocarbon accumulations under production in the basin.
At present, most of these fields are depleted and the gradual decrease in reserves is pushing the operator companies in Ukraine to look for the bypassed intervals in existing wells or explore new prospects. Another important aspect is understanding the actual formation pressure of each producing zone as it is a crucial piece of information for optimizing production. One of the logging technologies that is widely used to address these challenges is Multidetector Pulsed Neutron Logging (MDPNL). MDPNL has proved its efficiency in locating bypassed reserves that were missed during early open-hole evaluation and as well through monitoring the changes in formation properties that have occurred since the casing was set and production begun.
Enhanced Reservoir Insight and Precise Well-Placement in a Karstic Carbonate Layer With Real-Time Ultra-Deep 3D Inversion: A Case in a Horizontal Appraisal Well, Offshore Abu Dhabi, UAE
Authors: Wahbah Salima , Bellah Samir , Hattori Tadataka , Tsuda Ryuchi , fares Wael , Ghobashy Ahmed , Clegg Nigel 
Published: February 2024

Abstract
This paper details challenges in placement of an appraisal horizontal well. Challenges are associated with reservoir geology and well requirements. The top boundary of the fractured carbonate reservoir holds large uncertainties in depth and in structural dip and it also suffers from severe karsts. Well requirements are related to constraints on placing the horizontal well within a certain offset below the top reservoir to avoid the karst features while avoiding the potential for water or early water breakthrough.
Preparation, execution and evaluation phases of well placement demonstrates the importance of Morzhov the geosteering approach for successful completion operations in complex geology. An Ultra-Deep Azimuthal Resistivity (UDAR) tool was deployed as the main geosteering tool, because the low resistivity contrast between the carbonate reservoir and above shale is too small for conventional deep-resistivity tools to deliver on the well objectives. An advanced 1D inversion algorithm provides high certainty on detecting boundaries around 100 ft from the wellbore, allowing early identification of changes in the karstic surface. Pre-well Modelling enabled optimal tool selection and simulated 1D inversion responses to the challenging geology. Resistivity image and Nuclear Magnetic Resonance (NMR) were also included to improve geological understanding.
The horizontal section was targeted to stay within a certain offset below the top reservoir. At this depth, both top boundary of the reservoir and below water zone were mapped and identified by the real-time UDAR 1D/3D inversion. Moreover, a potential target zone was mapped at a deeper depth below the top boundary.
While geosteering to avoid karsts, the Borehole Assembly (BHA) was stuck and a sidetrack was planned based on the new real-time info obtained from the inversion in the first horizontal. The new deeper target zone was drilled and the UDAR Inversion mapped further karstic features. Towards the TD, the inversion showed a sharp boundary that correlates with a sharp Bit-Gamma ray increase suggesting another karstic feature. Application of UDR-Image-NMR assembly provides critical insights and comprehensions of appraisal areas; Laffan-Mishrif boundary is positively shallower than expected and a new unit with excellent properties is mapped and produced.
The appraisal well was successfully placed in the optimum zone, with oil saturation up to 69%. Mapping the upper boundary provided additional understanding of the geological uncertainty caused by the Karstic surface. Mapping of the aquifer allowed the assessment of the impact of changing the trajectory relative to the top boundary when required to increase distance from the upper karst boundary.
Lost Circulation Material Size Selection for Naturally Fractured Rocks
Authors: Nguyen K. , Mehrabian A. , Santra A. , Phan D. , Bathija A. 
Published: February 2024

Summary
This paper presents a scheme for designing lost Circulation Material (LCM) blends that are commonly used to mitigate loss of wellbore drilling fluid through natural fractures of rock formations. The method involves using the history of drilling fluid loss rates to estimate the mean aperture size of the formation natural fractures. This estimate is enabled via an inverse solution based on a nonlinear optimization algorithm to obtain the most likely value of the effective permeability of the natural fractures network. The inverse solution embeds a forward semi-analytical solution that models the displacement of formation rock fluid by the drilling fluid as the losses occur. The forward solution accounts for yield-power law rheology of drilling fluid and considers the formation fluid displacement occurring through a network of connected natural fractures, as opposed to a single isolated fracture. Once the mean aperture size is determined, a blend of selected LCMs may be recommended via a particle size criterion that optimizes the LCM particle size distribution for effective plugging of fractures. The overall LCM design scheme is discussed via a case study.
Rethinking Event Detection and Drilling Processes Using High-Speed Downhole Telemetry and MPD Know-How
Authors: Johnson A. , Boucher M. , Pink S. 
Published: February 2024

Abstract

Objectives/Scope
The objective of this paper is to describe how high-speed downhole telemetry and technologies developed for managed pressure drilling (MPD) may be combined to overcome the limitations of conventional surface-based event detection systems. This paper will discuss equipment and control system considerations in the exposition of a downhole event detection system.

Methods/Procedures/Processes
An evaluation of high-speed downhole telemetry in the context of an MPD operation was performed, uncovering the limitations of conventional and MPD event detection systems. Using simplified fluids physics models, this paper describes how a surface-based event detection system is disadvantaged in identifying changing or deteriorating downhole conditions. Examples include cases of gas solution following an influx and undiagnosed wellbore instability events. Downhole event detection systems and methods, which aid in the early detection of the events, are shared along with a discussion of applications of MPD technologies in non-MPD wells.

Result/Observations/Conclusions
This paper is a demonstration of the shortcomings of conventional event detection approaches. Nearly all contemporary event detection systems are surface-based, consuming surface-acquired data. The drawback of this approach is that downhole events grow in magnitude or scope undetected until an instrument detects a change at the surface. This may allow the downhole conditions to significantly depart from what the rig crew thinks is happening based on what they can see at the surface.
By combining downhole high-speed telemetry technology and certain components developed for MPD operations, a downhole event detection system can compare measured values from downhole tools with expected values from an online model. The downhole measurements represent the well as it is, whereas the estimates represent the well from the surface vantage point. Deviation between these two viewpoints occurs during key contingency events, implying that a change has occurred downhole that cannot be physically measured at the surface. As such, a deviation alarm may be set, which is triggered significantly before any surface-based event detection systems. Detecting problems and responding to the well early is essential to reduce the occurrence and impact of unplanned events.

Novel/Additive Information
Other information is shared regarding event detection system design and integration with other systems onboard the rig. Visualizations that simplify the interpretation of downhole-acquired data are shared. Additional considerations for rig integration are also discussed.
Maturation of Challenging Narrow Upper Gharif Channel Reserves: a Case Study from Central Oman Fields
Authors: Alsalmi M. M. , Sabahi A. A. 
Published: February 2024

Abstract
Gharif Rocks primarily consists of fluvial and coastal clastic sediments. They are regionally overlain by the AlKhalta formation of glacial origin. They are Early to Late Permian (Akhdar Group) in age and spanned a depositional period of about 20 million years.
There are three main issues related to Upper Gharif reservoirs and those are: (1) Reservoir Prediction (2) Connectivity & (3) Compartmentalization. These uncertainties have big impact on development decisions including, well count, well spacing & water flood management in most fields.
In this case study, some of these complex stratigraphic trap systems are explained & the risks of development were mitigated by building multiple geological conceptual models & smart phased development.
A Low-Speed Wind Turbine: An Offshore Application for Operational Greenification
Authors: Sedaralit M Faizal 
Published: February 2024

Abstract
A fossil fuel is undergoing transitional era towards clean energy envision, reducing carbon footprint is one of top priorities. This is unlocking factor for license to operate (LTO) and continue production from fossil fuel as based energy source. Power generation from open burning combustion i.e., gas turbine generator (GTG) is no longer an option. Moving forward, rather to reduce the CO2 emission to meet net zero carbon emission (NZCE) by year 2050. One of ways to mitigate this GTG problem is by replacing fossil fuel, methane as a feedstock to clean energy derive from wind power. The harvesting of wind energy is not an easy task as Malaysia offshore region is known as low wind speed environment typically below 7 meter per second (m/s) with average of 2m/s (Asia wind association energy, 2023).
The use of normal wind turbine for low speed wind region is not suited best for this mission to produce energy. Low wind speed in this region is fall under class S. Therefore, a new scheme of technology is needed to cater such requirement. The technology is called low speed wind turbine, which able to generate and store power up-to 4 megawatt (MV). With this invention, capable to solve existing brownfield operational paint point for decarbonation effort. This paper showcasing a case study for offshore Sarawak, Malaysia.
An integrated approach is adopted for seamless development between green field and brownfield scopes. A green field development refers to wind turbine installation and power generation and storage. Meanwhile, for a brown field scope is defined as tie-in, platform modification and GTG replacement. The novelty of this project, the platform is located offshore with a total water depth around 60 meters, in which cost for substructure is one of considerably high for development. The wind turbine technique is moving away from the conventional of substructure jacket installation, instead adopted of a tension leg platform (TLP) concept; it is floating structure with mooring system. Of course, integration with TLP is a tall tower that reaches up to 180 meters height as stand to rotor and blades. This enables wind harvesting at maximum of wind energy for a duration of 365 days per annum. A total integrated energy management system (IEMS) plays significant roles, and this include energy storage and power-up including battery and control systems.