bluuebunny/crossref_metadata_2025_split huggingface dataset:
Successful Drilling High Pressure Well with Depleted Levels: Field Lessons from Reservoirs in Offshore Jack Up
Authors: Antoniucci Cesare , Di Altobrando Cinzia , Gioia Valeriano , Tufo Marcellino , De Blasis Renzo , Ciancaglini Massimo , Santoni Fabio 
Published: February 2024

Abstract
Nowadays many mature fields are drilled worldwide, alternating depleted and pressurized levels. Depletion phenomena, due to long term production, increase problems associated to all well operations such as drilling, completion and production optimization. On drilling activities events like lost circulation, stuck pipe and wellbore instability are often observed.
This paper outlines successful experience in drilling reservoir showing depleted zones (0.76 kg/cm2 /10 m) alternated with high pressure formation levels (mud weight used 1.95 kg/l) and characterized by differential pressure values (difference between hydrostatic mud pressure and pore gradient pressure) around 480 kg/cm2. Such situation creates technical challenges and requires implementation of particular drilling strategies. Experience in mature field offshore combined to innovative technologies leads to successful drilling. Operative experience, use of Eni circulating device (e-cdTM), Eni NPT predictive tool (e-nptTM), proper mud type selection and optimized drilling BHA have been key factors in achieving the desired target.
E-cdTM: is a Eni technology that allows to maintain uninterrupted flow of drilling fluid into the well while adding (or removing) joints of "drill pipe" to the drill string, thus avoiding severe fluctuations in annular pressure, maintaining hole stability, decreasing stress formation and the possibility of stuck pipe events. E-nptTM: is a Eni software to real time monitoring drilling parameters and predict, based on Eni case experience, phenomena of Circulation Loss, Stuck pipe or Fluid influx. Mud type selection: oil base mud to mitigate problems due to high differential pressure; high performance water base mud (polymeric inhibited and encapsulated) to avoid reservoir damage even if the differential pressure value reached would have suggested to use oil base mud. Well proved BHA design with automated rotary steerable: to produce less stress to the formation without creating instability to the hole; moreover the BHA is equipped with annulus pressure while drilling (APWD) to monitor real time annulus pressure acting against the formation during drilling and near bit resistivity to allow proper casing point identification. Operatively it has been implemented, in enlarged phases, to uniform the hole at same size to optimize cementing operation of the column
This paper presents the successful Eni district South Europe experience in drilling, with minimal NPT, high pressure well alternating pressurized and depleted levels due to many years of production. Such achievement has been obtained combining the most recent technologies, both Eni properties and not, and operative experience gained over tens of years of activity.
Deriving the Unknown Sublayer's Pressure in Producing Gas Wells Using the Selective Inflow Performance Workflow
Authors: Rehman S. , Mirza W. H. , Espinoza I. B. , Farooq U. 
Published: February 2024

Abstract
The accurate measurement of sub-zone pressures is crucial for monitoring the performance of reservoirs in gas fields. However, this can be challenging due to the commingled flow of multiple reservoirs and sub-zones within a single well. In this study, we evaluated the use of Production Logging (PLT) and Selective Inflow Performance (SIP) workflows for computing sub-layer pressure in carbonate reservoirs in Pakistan.
The study was conducted on carbonate reservoirs located in Pakistan. The usual wells are vertical and have numerous perforations, resulting in combined production across multiple reservoirs and sub-zones. To determine the pressure of a specific sublayer, Production Logging (PLT) was carried out to collect data at various choke sizes. The data was then analyzed through Selective Inflow Performance (SIP) workflow. The Rawlins and Schell-Hardt equation was used to plot the relationship between flow rate and pressure, enabling analysts to match the trendline with the acquired data points.
The proposed analysis revealed that at least three different chokes should be tested during PLT logging to ensure accurate results. In addition, for accurate analysis it is preferred that a single-phase fluid is flowing at high flow rates, to be able to detect contrasts between inflows from different zones. In Case-1 SIP workflows were applied on two independent reservoirs with multiple sub-zone entries and found that Reservoir-1 had a current pressure of around 1480psi, whereas Reservoir-2, which was more depleted, contributing more than 80% to production had a current pressure of around 1050psi. Shutting down the wells showed an estimated crossflow of 0.43 MMSCF/D from one reservoir to another. The results demonstrated a good relationship between PLT estimated flow rates and pressures across all producing sub-zones. In Case-2, it was observed that the highest contributing layer on every choke size became a thief zone in shut-in conditions. Such kind of a reservoir that contain mulitple isolated stringers that are commingled together in the well make it challenging for reservoir management.
The successful application of SIP workflow allows to perform pressure time-lapse monitoring and adjust the dynamic model accordingly for future reservoir development. This study highlights the importance of periodically measuring sub-zone pressures for effective reservoir performance monitoring in gas fields.
Development of a New Retarder Recipe Containing Boric Acid, Which Exhibits Excellent Mechanical Properties Suited for the Mid Temperature Range (MTR) in Oil and Gas Well Cementing Operations
Authors: Ohochukwu Chioma , Mathew Samuel , Liang Zhang 
Published: February 2024

Abstract
In field operations with Bottom Hole Circulation Temperatures (BHCTs) ranging from 240F to 280F, a range of cementing retarders have been noted to exhibit shortcomings, particularly in their ability to effectively address the entire temperature range, particularly at the higher end. This research proposes a formula that offers greater consistency, reliability, and excellent mechanical properties throughout the entire temperature spectrum.
During the laboratory analysis of this study, the API 10B-2 method was selected as the preferred approach. This method was used to examine the thickening times associated with different concentrations of commonly employed mid-temperature retarders, with the aim of determining the temperature range at which the retarder exhibits its best performance efficiency. Subsequently, the recommended recipe, which combines Boric acid and a lignosulfonate-based product, was subjected to the same testing conditions to determine the highest achievable temperature at which it remains effective. The mechanical properties of the proposed recipe were also determined and compared to the industry minimum requirements.
The laboratory findings indicated that, when testing various concentrations of the reference mid-temperature retarders (MTRs) at different mid-temperatures, it was challenging to achieve extended thickening times, especially as the test temperatures approached the higher end of the spectrum (260F-280F). Some of these reference retarders, despite their claims to be suitable for mid-temperature use, fell short in extending thickening times beyond 220F. Others, which performed well at lower temperatures, lost their desired efficiency as the test temperatures increased, reaching up to 250F. However, the recommended recipe under investigation, which combines a consistent concentration of the lignosulfonate-based product with varying levels of Boric acid, proved to be reliably effective with improved thickening time performance across the entire temperature range, spanning from 240F to 280F, as well as satisfying and exceeding the minimum required mechanical properties in the industry.
This advancement introduces an industry-dependable mid-temperature retarder (MTR) formula that spans the entire mid-temperature range, enabling the design of both shorter and longer thickening times as needed which satisfies the minimum required mechanical properties for oil and gas well cement fluids.
A Systematic Cementing Approach to Improve the Shoe Track Integrity: Case Studies from Saudi Arabia
Authors: Ali Wajid , Al Turki Faisal Abdullah , Bouaraki Mouloud , Lawrence Don Woody 
Published: February 2024

Abstract
Incompetent shoe tracks are typical in oil well cementing and cost many hours of lost rig time for remediation. An incompetent shoe track results from unset, severely contaminated, or no cement inside the casing section between the float collar and shoe after a primary cement job. This paper will address several case studies where a systematic and engineered approach was utilized to apply various solutions that helped to improve the shoe track integrity.
The wet shoe has been of the utmost attention to oil and gas companies, as expensive remedial cementing operations are needed to repair the deficiency in shoe track integrity. After a thorough process review, many opportunities were identified to improve the cementing basis of design, such as lead and tail slurries for liners and multiple stage jobs, increased length of shoe track, the addition of bottom wiper plugs, and the use of lost circulation material in the spacer and cement slurries. This paper illustrates the case studies where the above-stated methods were successfully applied to improve the shoe track integrity.
Some of the major contributing factors to incompetent shoe track integrity were identified as attempting to cement the long sections with a single slurry, excessive thickening time requirements to accommodate the operation of liner hangers and stage tools, over-displacement of cement during placement, overestimated bottom hole temperatures, severe or total losses during cement placement, cement slurry contamination by the lack of a bottom wiper plug, and picking weak casing point. It was also observed that the consequences of poor shoe track integrity were amplified in challenging drilling environments where formations were either reactive, hard and abrasive, abnormally pressured, high downhole temperature, or prone to lost circulation. As a result, an increased effort was put in place to eliminate the poor shoe track integrity by implementing the opportunities identified during the process review. Cement inside the shoe track was found to take more weight on bit and have a slower penetration rate during drill out. Also, the required casing and formation integrity tests were achieved even in areas historically prone to compromised shoe track integrity. This confirmed the success of this systematic cementing approach and helped revise the basis of design.
This paper presents a detailed study of the novel engineering process that was successfully deployed to plan and execute the primary cement jobs with the assurance of shoe track integrity. In addition, this paper highlights the systematic approach utilized to eliminate or mitigate the occurrences of incompetent shoe track integrity with observed improvement in field deployment results.
Integrated Subsurface Development & Planning (SSDP) Dashboard for Surveillance, Optimization, Cost Reduction and Streamline the Decision-Making Process in Mature Field, Pertamina Hulu Rokan Zona 4
Authors: Gilang Alfian , Saribu Juanda Dolok , Renditya Ardiansyah , Fariz Muhammad , Fernando Elrey 
Published: February 2024

Abstract
In the midst of digital transformation, Pertamina’s management and workers are required to be able to adapt to the new environment in achieving company goals. One of the tools to make it easier to monitor and make quick and precise decisions is the use of an integrated dashboard. This increases the optimization of the execution of a work plan and saves costs from work plans each year.
Integrated SSDP Dashboard is a Zone 4 workplan monitoring dashboard that integrates rig barchart data, production, development (Plant Of Development, investment decisions, reserves & resources) and well realization with the following stages (1) Input – gathering data from any source file, (2) Process – Analysis and formulate integrated data and calculation, (3) Output - Dashboard finalization with executive results in accordance with standard templates, interactive visualization to facilitate data analysis and decision making, dashboards are updated regularly. Also streamlines reporting to regional/central offices.
This dashboard provides the ability to take standardized data at a high level so as to save time in presenting reports. In addition, integrated data can help workers to the management level in determining planning after which it will increase company profits. Its massive use can have a positive impact on business processes in the company.
The dashboard is generated from the integration of data from various divisions in Zone 4 which is interactive, user-friendly and can facilitate the needs of the worker level to management so that the productions & resources monitoring process runs optimally. The optimization rate in management decision making using SSDP Dashboard is 96%. Dashboard succeeded in making cost efficiency related to drilling costs (rig rental, materials, and services) cost allocation of ± $65 million OTOBOSOR (on time, on budget, on schedule, on return) in the current year and loss of production due to Drilling & WO work plan which retreated ± 6,200 BOEPD. Reports received by management are dynamic (Power BI through Ms Team) where the process of retrieving supporting graphs and tables takes ± 5 seconds. Data is successfully protected through Pertamina’s corporate account authorization to the share folder. The level of ease of evaluation process for monitoring workplan reached 97% more than the target of 85%.
Using Data-Driven Analytics Workflow to Find out Highly Watered-Out Mechanism and Novel Solution in Horizontal Wells for Heterogeneous Carbonate Reservoir
Authors: Hu Dandan , Li Wenhuan , Li Qianyao , Chen Yihang , Wu Yuanbing , Hu Songhao 
Published: February 2024

AbstractK reservoir is a highly heterogeneous pore carbonate reservoir with thin layer and high permeability zone at the top. It adopted the overall horizontal well pattern, the water cut rose rapidly and "double-inverse" water flow dominant channel formed subsequently after water injection. The water cut of most producers rose rapidly to more than 85%, resulting in a large decline of oil production and poor sweep efficiency.In the paper, a novel methodology and data-driven analytics workflow was established for detecting the characteristics of watered-out horizontal wells, revealing the highly watered-out mechanism, describing the residual oil mode on different main factors and proposing the solution for highly watered-out horizontal wells. The paper analyzed the rules and characteristics of water cut change after water injection and clarified the effect of the matching relationship of horizontal well trajectory and the main factors on the rapid rise of water cut. To diagnose the mechanism and reasons for the rapid rise of water cut, the watered-out conditions have been described for producers, injectors and inter-wells in longitudinal direction at different times through passing wells from lower formation based on logging data. The paper put forward the theoretical calculation formula for liquid effusion of horizontal well bore and the prediction formula of liquid discharge time. By discharging the accumulated liquid from the well trajectory at the high permeability zone, the residual oil with the well trajectory in other layers could be used to expand flooding volume, reduce the water cut of the producer, and restore the normal production for these high water cut wells. It was indicated that the actual incremental oil result for these wells were decided by the relationship of well trajectory and the main controlling factors and the remaining oil distribution.This workflow has successfully been applied to a giant heterogeneous carbonate reservoir. The water cut of most wells was significantly reduced, with an efficiency of more than 90.0%. The time of liquid discharging and water cut controlling was 1 and a half months to 4 months, and the water cut decreased between 8% and 24%, and the total incremental oil of 2 million barrels has been achieved.Strong heterogeneity in carbonate reservoirs of Middle East generally develops and easily causes high water cut for producers, the innovative strategies in the paper has good adaptability and reference for these reservoirs.
Application of Multi-Scale Fracture Identification in a Shale Gas Reservoir in Southwest China—A Case Study
Authors: Qin Qiuping , Jiang Tingxue , Zeng Yongjian , Bian Xiaobing 
Published: February 2024

With the development of seismic acquisition methods, research theories, and application of various interactive interpretation software, the application of seismic technology has developed from structural interpretation to reservoir evaluation [1], lithology interpretation, reservoir description, fluid identification and other aspects. Multi-scale fracture identification driven by seismic data has been widely used in the development of shale oil and gas reservoirs. Due to the introduction of coherent data, artificial intelligence and visual interpretation software in recent years, the ability and accuracy of fault structure identification based on seismic data have been greatly improved. The methods used to predict fractures with seismic data include shear wave splitting detection [2, 3], conversion wave fracture detection [4], longitudinal wave anisotropy detection and post-stack seismic attribute method. Post-stack seismic attributes contain rich lithology and physical property information, which is the most widely used fracture prediction method at present. However, its structural interpretation is mainly based on the seismic waveform characteristics of Inline and Crossline profiles extracted from seismic data. Due to the small fault distance, the characteristics of in-phase axial dislocation in time profiles are not obvious. In addition, part of the time section is missing in the seismic interpretation grid line, which determines that the interpretation precision of micro-structures such as small faults is low.
Based on the 3D post-stack seismic data, well logging and 5 horizons interpretation data a shale gas reservoir in southwest China, we carried out the multi-scale fracture identification research. The whole working area is about 200km2, and the fracture development of the Longmaxi Formation buried to a depth of 3700 ~ 4200m is the focus of the study. In order to achieve a more accurate and effective interpretation of small and medium-sized fractures and other micro-amplitude structures, the research on seismic multi-scale fracture identification of small and medium-sized fractures is carried out on the three-dimensional seismic data in the study area. Combined with the seismic and geological data, the fracture display of the whole area is enhanced by structure-oriented filtering. The machine learning method has a good application effect on large fracture identification. The fracture identification algorithm based on CNN (Convolutional Neural Network) image segmentation transforms the problem of image classification into the problem of image segmentation. The CNN network based on U-net is used to identify large-scale fractures. And then d-LoG (Laplacian of Gaussian Operator) coherent sensitive to medium-small scale fractures are extracted. Finally, the identification results of large, medium-small scale fractures are fused to evaluate the development of fractures in the working area.
Utilizing Advanced Rotating Control Heads Technology to Enhance Safety While Drilling a Challenging Exploratory Well - A Successful Case History
Authors: Haq Mohammed Aleemul , Omer Mohammed 
Published: February 2024

Abstract
The drilling operator wanted to improve hydrocarbon recovery during drilling a development well using rotating control devices (RCD) for the upper 17-1/2" hole section.
The challenge to drill this section was shallow gas that can lead to a kick. To drill these formations conventionally would increase the risk of the well taking a kick that could directly affect the time required to drill the well to its target depth. A closed-loop system was used to anticipate the well taking an influx of shallow gas while drilling this formation. In the event of the well taking an influx, the influx can be safely diverted with RCDs away from rig floor.
A closed-loop drilling system was created by installing the Rotating Control Device on top of a 21-1/4" 2K Annular BOP prior to drilling the 17-1/2" section. With this closed-loop system any shallow gas influx can be diverted away from rig floor, thus improving safety to personnel. Another advantage of using a RCD is that the operation can be switched to conventional mode directly without have to rig down the RCD system. Also, using RCD will not interfere with the rig’s well control system.
The primary objective of utilizing the RCD was to enhance safety while drilling the development well which contained known hazards already assessed from drilling the previous well. RCD 7800 was utilized to mitigate drilling hazards generated from the loss circulation, gas migration, influx, and the presence of shallow gas. All the objectives were achieved: establishing a closed circulation system, additional safety in drilling a formation containing gas, and ensuring control of return flow.