bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity Analysis and Cost Analysis for Casing Designs (Case study)
Authors: Abbood Husam Raad Abbood , Alkamil Ethar Khalil , Miftah Karrar Riyad Miftah , Al Dhaheri Amgad Hamad Khalaf , Al Luaibi Ibrahim Salim Abdullah , Almaarij Muhammed Adnan Khudhaier , Alhilfi Ali Hassan Jaber , Hamad Zamzam Neama Hamad 
Published: February 2023

AbstractThe oil and gas industry is witnessing an increasing demand for more cost-effective well design and operations. Thus, the scope of the operator company's planned new processing capacity aims to attain a competitive cost and schedule. In this work, slim versus fat casing designs are evaluated in price and technical challenges, including removing rig/skidding, drilling, and ensuring well suspension.Data from ten (five slim design and five fat design) wells in southern Iraq was quantitatively analyzed. Attaining the project's target requires that the well be drilled as a deviated well (S-type). The analysis includes the cost of CSG, lost circulation, lost curing, lost circulation materials, volume of the cement plugs to cure losses, non-productive time, stuck pipe and differential sticking, and cement bond quality. Moreover, a cost analysis is conducted by considering all of a project's relevant factors—including economic and technical considerations—to ascertain the likelihood of completing the project.The finding emerged that the amount of lost mud and the average cost of addressing losses were higher in slim than fat designs. The slim design is associated with higher volumes of cement plugs for curing losses than the fat design. As per NPT analysis, the time required to fix losses emanating from slim design was 62% higher than fat design. A critical observation emerged from the study that while differential sticking failed to occur in both designs, stuck pipes happened in some of both designs. The cost analysis of slim and fat designs focused on the cost of drilling, CSG, wellhead, diesel, and fueling is also done. The total cost of the fat design amounted to approximately 53.67%, while the total cost of the slim design was about 46.33%. This made the slim design's cost savings ratio of roughly 7.34%. Meanwhile, given that similar issues may occur in the proposed well design, the following measures have been isolated to help tackle such problems. (1) Optimize mud design to inhibit Tanuma formation Clay swelling issues (2) Reduce OH time to avoid Tanuma's time-dependent clay swelling. (3) Reduce the inclination across Tanuma to 20 degrees.Finally, this paper describes how two casing designs are successfully engineered and executed and serves as a guide for selecting proper candidates for this design. Also, it is an operational guide for two casing designs, slim and fat, to ensure that these challenging long open holes will be successfully and economically drilled while minimizing risks and ensuring compliance with the well delivery process.
Automatic Lithology Classification of Cuttings with Deep Learning
Authors: Nanjo Takashi , Ebitani Akira , Ishikawa Kazuaki , Konishi Yusaku , Miyoshi Keisuke , Shulakova Valeriya , Beloborodov Roman , Kempton Richard , Delle Piane Claudio , Benedict Clennell Michael , Sagotra Arun , Pervukhina Marina , Mizutani Yuta , Harada Takuya 
Published: February 2023

Abstract
Describing cuttings is routine work for wellsite geologists on a drill rig. The time-consuming nature of this analysis and the lack of consistency of the results between different interpreters are the two major concerns for this task. Wellsite geologists spend approximately 70% of their time on cuttings descriptions. In addition, 2 to 3 wellsite geologists are generally assigned to a drilling campaign, and they are replaced at the end of a shift. ML/AI techniques have the potential to solve these issues because of their advantages in prediction speed, objectivity, and consistency. The authors’ aim is to automate the task of cuttings descriptions with ML/AI techniques.
We are targeting four lithologies, namely sandstone, mudstone, volcanic (volcanic rocks), and carbonate (carbonate rocks). The cuttings were collected from six wells in the Browse Basin (Australia). Of these four lithologies, a total of 1978 cuttings images were taken under a stereomicroscope.
We chose a semantic segmentation technique using Convolutional Neural Network (CNN) algorithms to perform the image classification task. The images were labelled using the open-source annotation software. This annotated data were used for the network training. The labelled images were split into training, validation, and test sets.
The accuracy of the trained model was evaluated using the intersection-over-union metric (IOU). The mean IOU of the final model on the validation dataset was 82.3%. Prediction results on the cuttings that are represented by single lithologies are qualitatively very accurate. On the other hand, the prediction for the non-typical lithology (e.g., siltstone, dark-colored volcanic rocks, mixed lithology samples) has room for improvement. The fragments with similar textures (e.g., dark colored volcanic and dark mudstone) are complex for the CNN to identify. The final goal of our project is not only the lithology identification but also the quantitative estimation of lithology abundances in the cuttings. Additional model improvements, such as hyperparameter optimization and significantly more training data, are required to accomplish this task successfully.
The trained model for cuttings description has the potential to realize quantitative and high-speed cuttings description. Well-trained AI/ML models have the potential to assist well site geologists by automating the cuttings description process simplifying, speeding up and improving the consistency on the rig floor.
Oscillation Fishing System: A Novel Approach to Improve the Chances of Freeing Shallow Mechanical Stuck Pipe
Authors: Han Kyungnam , Alharbi Sultan , Albaqshi Ahmed , Eltoum Ahmed 
Published: February 2023

AbstractOne of the most common and costly situations in drilling operations is stuck pipe recovery, as it results in significant non-productive time (NPT). Stuck pipe is often freed by applying axial jarring forces to the string to overcome the sticking force. However, becoming stuck at a shallow depth often results in insufficient pipe stretch in the string to generate enough energy to free the stuck pipe using a jar.In cases where it is not applicable to use a jar, the use of the Oscillation Fishing System (OFS) is a more effective technique and an optimal solution to free the stuck pipe. Using the OFS to free stuck pipe encompasses generating continuous oscillatory axial motion. Pressure pulsations generated within the tool are converted to steady axial oscillations using the springs in the tool. This continuous motion produces axial forces at high frequencies, which translates to continuous energy applied to the stuck pipe.The OFS is used in different fishing applications, such as vertical and directional well profiles. The technology is used to free stuck pipes in cased and open holes. Depending on the stuck situation, the OFS is either placed at the surface or downhole with conventional bottom hole assemblies (BHA). In the subject applications, the OFS was run at the surface to free both motor and slick rotary BHAs in large hole sizes, 22 in. and 16 in., in different scenarios.This paper will analyze four examples where the OFS was used in a similar application. In all these examples, conventional stroking tools (i.e., fishing jar) were not part of the system and jars were not used to avoid the potential hazards of impact forces affecting the rig floor. Moreover, activating jars at shallower depths is ineffective as it requires a longer length of pipe to generate enough energy to free the stuck fish. The OFS was used after unsuccessful attempts to pull and recover the string. When the OFS was activated at the surface, producing continuous axial movement, it successfully freed the stuck fish.A new application of the OFS in fishing operations was introduced by using it in the surface sections. Not only did the OFS eliminate the extra steps required to get closer to the stuck point, but also it saved rig time and drillstring components and prevented the need for sidetracking. This paper discusses the use of the OFS at the surface in three examples, including an analysis of the performance to free the stuck string.
Unlocking Gas Production Potential for Ultra-High H2S Reservoirs: Closed-Loop Testing Avoids Flaring and Toxic Gas Release
Authors: Alaithan Monaf S. , Leal Jauregui Jairo Alonso , Al-Hazmi Waleed Ahmed , Sarac Sukru 
Published: February 2023

AbstractFlowback operation of ultra-high H2S gas well is a challenging scenario due to complex environmental considerations, equipment limitations and limitations on surface flow management with unstable well conditions. This paper will present an application where flaring impacts were significantly minimized and no H2S gas was released to the atmosphere, unlocking the production potential of high-H2S formations.Then, a new Technology concept is being developed. A brand new Closed-Loop Testing package has been implemented to overcome the flowback limitations with high H2S concentration and minimize flaring during well clean-up. Simulation results of expected wellbore dynamics during well start-up were studied to optimize flowback package fluid handling capacity and perform safe operating conditions. New inline measurement devices were used for H2S, CO2 and inline density measurement were key on providing in-line well monitoring parameters as well as better decision points and control in key elements and including; new control valve metallurgy, new metal-meat seals, new PRV design/metallurgies, new EE-NL pipeline, new approach in low pressure systems, pressurized storage vessels both condensate and water, as well as avoid any human exposure for critical procedure including water, PVT sampling and gas metering validations. This new approach allows to complete this task without releasing toxic gases to the atmosphere. Selected equipment also allowed continuous flow to clean-up the wellbore and safely transfer the fluids to the production line, minimizing flaring while avoiding any environmental impact.Wellbore behavior during well kick-off was as expected based on the transient wellbore and reservoir simulations, which helped achieve a continuous flow to safely flow the wellbore and handle the produced fluids. The selected closed-loop testing set-up in addition to continuous well monitoring with new inline measurement devices allowed remarkable flow management optimization. This reduced CO2 and toxic gas emissions, minimizing environmental impact. Toxic gas release in the flowback area was also avoided by eliminating manual measurements with the closed-loop testing package. The wellbore was cleaned-up to achieve the production tie-in criteria. This implementation acts as a proof of concept to flowback high-H2S wells.This paper presents the new testing equipment and practices to enable safe flowback in high and ultra-high H2S conditions. The example explained in this paper is the first post-stimulation wellbore flowback in Saudi Arabia, including ultra-high H2S conditions being achieve by a new closed-loop well-testing package.
Vertical Seismic Profile Modelling and Applications for a Deviated Well to Improve Surface Seismic Interpretation
Authors: Negenman Brendon , C. A. Razak M Amin Nizar , Yusof Ahmad Izzuddin 
Published: February 2023

Abstract
Vertical seismic profile (VSP) data is a powerful calibration tool that helps to link the time (surface seismic) & depth domains (well logs). Conventional rig source VSP data is not recommended to be used in a highly deviated well for seismic calibration. Excessive ray bending from the source-receiver offset will cause errors in the vertical time calculations, and this data will not be reliable to calibrate the surface seismic. This paper will discuss a case-study for a highly deviated offshore well using a vertical incident VSP (VIVSP) source geometry.
A VIVSP is a unique type of geometry that places the source above the receiver array. This is usually done using a supply vessel for an offshore environment. Placing the air gun source above the receiver ensures vertical raypaths, and this gives the most accurate TWT result. Planning is crucial for this type of VSP to calculate the number of receiver arrays & source positions. 2D ray trace modelling using the surface seismic interval velocity & VIVSP geometry was used to verify the data would be within tolerance for vertical raypaths, and to optimize the acquisition time.
VSP data was acquired using the optimized vertical incidence geometry. Data quality was excellent which gave a reliable time-depth profile for most of the well interval. VSP data was processed to corridor stack. and CDP transform was used to create an image below the well trajectory. This data was used to calibrate seismic velocity during seismic processing, as well to tie surface seismic to well.
Application of Biosteered Underbalanced Coiled Tubing Drilling in Optimizing Production
Authors: Alshuhail Faisal , Alsaad Mohammed , Alqahtani Mahboob 
Published: February 2023

AbstractExecutive SummaryThe objective of this study is to compare the performances of Underbalanced Coiled Tubing Drilling (UBCTD) versus conventional drilling with stimulation in a Permian carbonate target within a field in Saudi Arabia. The focus of this study is to ultimately investigate the effectiveness of biosteering in UBCTD compared to geosteering and subsequent stimulation in conventional drilling of vertical and horizontal wells within the same target.Biosteering is an application of biostratigraphy used to navigate and maintain well paths within the desired zone. This technique has been employed successfully in UBCTD wells in the Middle East. Biosteerers utilize the characteristic distribution of microfossil assemblages obtained from cuttings samples with the identification of biozones based on existing schemes. The most effective way to geosteer these well is to use this technique in conjunction with lithology descriptions, GR log trends, visible porosity and drilling parameters. UBCTD wells are not stimulated as there is minimal induced formation damage during drilling operations. Geosteering utilizes logging while drilling (LWD) in horizontal wells for lateral placement and to determine perforation intervals. Conventional wells in this study are all stimulated, employing multistage acid fracturing techniques. The dataset in this study comprises 50 wells, all of which are compared by normalized post-completion performance.Post-completion performance from the 50 well dataset was normalized to achieve a representative comparison. UBCTD biosteered wells show indicative superiority when compared to horizontal and vertical conventionally drilled and stimulated wells. In addition to the minimal formation damage in underbalanced wells, footage in the target is higher in biosteered UBCTD wells compared to geosteering. This is due to several reason with the main reason being is the ability of UBCTD to drill multiple laterals in each well, thus maximizing target contact. A detailed look into two wells targeting the same formation and field proved effective UBCTD utilization, yielding a production increase of several orders of magnitude.Despite these results, the normalized production performance may not account for significant LWD merits. In terms of steering, UBCTD slim-hole nature limits applications of available LWD technologies that provide essential information for reservoir characterization and development plans.
Online Measurement and Analysis Technology of Oil & Gas Multiphase Flow by Magnetic Resonance
Authors: Deng Feng , Chen Shiwen , Chen Guanhong , Wang Mengying , Liu Chao 
Published: February 2023

AbstractIn the petroleum industry, there is a huge demand for oil & gas multiphase flow metering and fluid property analysis. In addition to common production metering and economic transfer, it also includes downhole metering, drilling and completion fluid testing, oil testing, gas testing, storage and transportation testing, etc. This is an important parameter that needs to be mastered to provide flow guarantee for oil and gas production and transportation. So far, the multi-phase flow measurement methods are usually with low-efficiency, low-accuracy, high-costs and delay-delivery, and hard to reflect the real instantaneous fluid producing properties at wellheads or pipelines. Magnetic resonance (MR) technology is considered to be the most promising multiphase flow measurement technology, but at present it also needs to solve technical problems such as low measurement frequency, static measurement of phase holdup, poor environmental adaptability of the instrument, and high cost.Based on the previous work, this paper addresses the problem of low measurement frequency and inability to flow measurement with traditional low-field MR measurement methods, and proposes a dual-antenna measurement method, which increases the measurement frequency from 0.2Hz to 1Hz, and realizes online measurement of phase contents. A novel integrated probe structure is proposed, which widens the working temperature from -30 to 80 °C, increases the pressure range to 40 MPa, improves the anti-electromagnetic interference ability, and increases the measurement range to 600,000 cubic meters/day for the gas phase, while reducing the cost.The instrument has carried out various tests in 50+ wells in China, and the liquid phase measurement error is less than 5%, and the gas phase measurement error is less than 10%. This progress further helps to apply the NMR technology to oil & gas production industry, to realize green, efficient, online, low cost, full range multi-phase fluid measurements. The on-site fluid properties analysis capability moved the laboratory test to the oil & gas fields, improved efficiency, accuracy and reduce costs.As a flowmeter, the device reduces the amount of measuring equipment needed and manage wells more efficiently, as a ‘fluid analysis laboratory’, can provide the first-hand information on the oil/gas properties.
Well Optimisation Technique with Backward Elimination Process for Greenfield Gas Development
Authors: Vardcharragosad Pichit , Doungprasertsuk Chonlada , Srisuriyon Jantakan , Hamdan Mohamad Kamal 
Published: February 2023

AbstractThe well optimization technique with backward elimination aims to determine the optimum number of wells and their locations that can maximise project value and its recoverable resources, through repeated ranking of candidate wells and eliminating the poorest performer. For a greenfield development, subsurface uncertainties are typically still very large due to limited data from exploration and appraisal wells. This study outlines our approach to perform well optimization with these governing uncertainties in order to support the decision-making process.First, multiple realizations of reservoir models are constructed to represent range of possible outcomes by sampling different values from uncertainty parameters. Backward elimination for well optimization is then performed on those realizations. Wells can be ranked based on means and standard deviations of their performance, and the lowest rank candidate is eliminated from the process one at a time. At this point, project economic and resources are evaluated to find optimum set of wells for field development. Furthermore, well performance data from multiple realization models are carefully analyzed to define key subsurface uncertainties that need to be managed.Solution from this backward elimination with subsurface uncertainty workflow can maximize project valuation because it balances the risk of overspending to drill sub-optimum wells in some realizations with the risk of losing sell opportunity due to insufficient field deliverability in the other realizations. Development decision will be more robust because it is based on the optimum configuration that is applicable irrespective of the unknown uncertain quantities. Moreover, detailed analysis on well performance data allows us to better understand the risk associated with our planned wells so that appropriate de-risking plan can be developed and combined into development strategy.The backward elimination process is straightforward to implement and normally does not require very high computational expense. Thus, it is suitable to be used with uncertainty workflow with multiple realizations of reservoir models, which will increase computational requirement by multiple times. Other commonly used techniques for well optimization such as a Genetic Algorithm (GA) or an Evolutionary Algorithm (EA) are computational expensive by themselves already; and they will require even more runtime when using them with this uncertainty workflow.This paper extends backward elimination approach for well optimization to be used with uncertainty workflow. The overall uncertainty analysis workflow is discussed and provided, with key steps detailing the approach taken. Project valuation and recoverable resources can be further optimized with this new approach, and ultimately can guide the decision making in field development.
Extended Abstract: Complex Offshore Well Intervention Now Possible by Using Thru-Tubing Bridge Plug to Produce By-Pass Zone and Isolate Lower Production Zone
Authors: Eyuboglu Sami , Siregar Erlangga , Andhika Banu , Murvianto Febrian , Yuliarosa Zandra , Siahaan Patria 
Published: February 2023

AbstractIsolating lower production zone (water shut-off) and finding new perforation intervals from another reservoir zone is a typical well intervention application in mature fields. In normal conditions, legacy permanent barriers (Through Tubing Bridge Plugs -TTBP) have been used in those applications very successfully. However, challenges are posed by, well bore restrictions (passing smaller OD restrictions), rig height, reliability and setting validations with legacy tools in harsh environments and well conditions. This paper discusses the challenges during offshore well intervention operation in Indonesia due to the limited space for rig-up, limited crane lifting capability, and un-manned well platform with only daylight operation and the solutions for these challenges with new slim-sized TTBP technology and the slim-sized Pulsed Neutron tool.Critical success factors of this operation included providing valid gas saturation data by using a 1 11/16" Pulsed Neutron tool (TMD3D) to determine the remaining gas in producing interval and any bypassed opportunities; establishing enough force by using a slim size electromechanical setting tool (DPU) to set the 1 11/16" TTBP at the desired depth and establishing a mechanical barrier which can hold up to 1200 psi differential pressure until a cement cap can be established; and running a perforation simulation to select the right gun to create an effective perforation tunnel between the wellbore and the formation for optimized gas production from the bypass zone.Despite all the challenges, a good mechanical barrier was established to isolate the lower water production zone and successfully determine gas saturation in bypassed reservoirs by using the Pulsed Neutron data. Perforation intervals were selected with the pulsed neutron analysis. After perforation, significant gas production was established which was 50% higher than predicted. New slim-sized technology tools resulted in flawless job execution with their high reliability and cost-effective solutions without any service quality issues. In addition to increased gas production, efficient operation resulted by completing the job one week earlier than scheduled, which provided extra cost savings. This case study identified the challenges in complex well intervention operations and provides a valuable water shut off solution by using new 1 11/16" TTBP and 1 11/16" DPU technology. The solution has proven to provide tremendous cost saving for production enhancement activity.