bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eliminating Packoff and High Circulating Pressure During Well Cementing
Authors: Pleshkov D. , Taylor A. , Mora K. , Lozada A. , Pazmino D. , Sanchez Gould M. 
Published: February 2025

Abstract
This paper presents the successful well cleaning enhancements, cementing optimizations, and centralizer selection that were used during the deployment and cementing operations of liner string installations in a 20-pilot-well project in Ecuador.
Statistically, most of the packoff events in Ecuador during liner cementing have occurred in directional and horizontal wells where the presence of unstable limestone and shale zones affects openhole stability and geometry. Packoff events have been observed in most fields in Ecuador, but the study presented in this paper focused on only four fields: Auca, Shushufindi, Ron, and Villano.
In the past, high circulating pressures and packoff incidents have caused significant problems for well construction in these fields. Every packoff event was classified as catastrophic and often led to remedial cementing, sidetracking, or even well abandonment in severe cases. Operators favored expandable liner hangers because of their larger bypass areas, higher activation pressures, and the ability to rotate and reciprocate the string during cementing operations, which helps prevent premature activation of the hanger setting tool from high circulating pressures. However, packoff events continued to occur even with the use of expandable liner hangers, leading to an assumption that the problem was much larger and not associated solely with the liner hanger's geometry and operating pressures (Torres 2016).
The study of the problem began with an analysis of historical data from 150 wells that were completed with expandable liner hangers and experienced high circulating pressures.
The study revealed that despite using expandable liner hanger technology with a larger bypass area than that of conventional systems, 62% of the 150 wells had still experienced high circulating pressures and packoff behaviors of varying severity. This indicated that job parameters, rather than mechanical limitations, might have been the primary cause. Furthermore, an analysis of solids recovered from liner installations, which were identified as shale, led to a reassessment of hole cleaning procedures, the fluids used, and the cementing program.
A set of recommendations on wellbore cleanout, cementing fluids, pumping schedule, liner hanger technical requirements, rotation and reciprocation during cementing, and centralizer type and placement was developed and implemented for the 20-well pilot project. This involved multiple operators and fields and was used to test theories regarding the causes of high circulating and packoff behavior. A majority of the 20 wells did not experience any high circulating pressure or packoff behavior, and none of these wells required remediation work (Pleshkov et al. 2025).
Analyzing Polymer Flooding Strategies for Enhanced Profitability in Water Cut Management: A Case Study of a Sandstone Field in Kazakhstan
Authors: Sagandykova Dilyara , Shakeel Mariam , Pourafshary Peyman 
Published: February 2025

Abstract
The application of polymer flooding is under investigation to control water-cut and recover residual oil from a giant sandstone reservoir in Kazakhstan, where the water-cut in most producers exceeds 90 %. This study investigated an innovative approach to optimize mobility control through changes in polymer injection mode. Slug-wise and tapered polymer flooding techniques were examined to assess the feasibility of achieving effective mobility control with reduced polymer quantities and cost. Additionally, the study explored altering the polymer solution temperature to activate the synergy of mobility control and thermal effects.
Incremental recovery values achieved through these methods were compared to conventional polymer flooding. Slug-wise polymer injection yielded an oil-to-polymer ratio 16 times higher than conventional flooding, while tapered flooding resulted in a 38 % OOIP incremental oil recovery with 81 % lower polymer consumption. Hot polymer flooding improved incremental recovery by 4 % compared to conventional flooding. These results indicate significant cost savings, especially with tapered and slug-wise techniques, emphasizing their economic advantages.
Applying hybrid enhanced oil recovery mechanisms presents an opportunity to reduce project costs. For instance, achieving comparable results with lower chemical concentrations is of practical significance. The potential impact of this work on enhancing the profitability of chemical enhanced oil recovery within the sandstone reservoir under study is critical for the oil company.
3D Geomechanical Modeling and Application of Upper Clastic Rock Formation in Penglai Gas Field, China
Authors: Xinyu Guo , Ming Tang , Lu Zou , Long Zhang , Yuemiao Zhou , Shiming He , Xianghua Deng 
Published: February 2025

Abstract
The Penglai gas area, with a predicted reserve of 2005 billion cubic meters, is a crucial block for natural gas resources in the Sichuan Basin. In the upper clastic rock formation, drilling accidents such as wellbore expansion, sloughing sticking, tight sticking often occurs due to unstable wellbore conditions. The root cause of these incidents lies in the inaccurate predictions of the geological mechanical in the work area. To achieve safe and efficient drilling, this paper proposes a multi-faceted geological mechanical modeling approach. Firstly, the model utilizes well logging data, rock mechanics experiments, and in-situ stress experiments to finely characterize the rock mechanics parameters and in-situ stress parameters of the upper clastic rock formation in the Penglai gas area. Secondary, a three-dimensional velocity model is employed to establish a three-dimensional geological model of the upper clastic rock formation in the Penglai gas area. By utilizing the preferential sequential Gaussian simulation method, three-dimensional rock mechanics data volumes and three-dimensional in-situ stress data volumes for the work area are obtained. Compared with the logging calculation parameters of the verification well, the error of the three-dimensional model is less than ± 10%. This approach enables the accurate acquisition of rock mechanics parameters and in-situ stress parameters for the target well based on the coordinates and trajectory of the wellbore during drilling design and execution processes. The results of applying the model in 7 wells show high accuracy, with an average reduction of 2–3 bit sticking incidents compared to adjacent wells. The average wellbore expansion rate has decreased from 6.57% in the early stage to 2.71%. The occurrences of complex conditions such as gas influx and wellbore collapse have significantly decreased, and the drilling cycle has been shortened by an average of 24.76%. The results demonstrate that this model is capable of accurately predicting rock mechanics and geomechanics in the upper clastic rock section of the Penglai gas area. This provides a solid theoretical foundation for drilling design and real-time adjustments, offering essential support for the safe and efficient drilling operations in the Penglai gas area.
Abnormal Events Detection During Drilling Based on Knowledge Embedded Real Time Data Analysis
Authors: Shi X. Y. , Ji Y. , Cui M. , Guo W. H. , Tian Y. M. , Wu D. , Jing L. Z. , Yang X. Y. 
Published: February 2025

Abstract
Recognizing the signs of abnormal events during drilling at an earlier time and adopting appropriate action can greatly reduce non-productive time and improve drilling safety. However, due to the complexity of the drilling system and the uncertainty of data measurement, detecting abnormal events accurately and timely is not a trivial task. This paper proposes an early abnormal events detection approach based on real time data mining and knowledge reasoning.
Based on the theoretical analysis, field experience and historical data analysis, main indicators of abnormal events (e.g. kick, mud losses and pipe stuck) under different drilling operations are identified, and this knowledge is represented as logical rules embedded in an event detection model. Various time series analysis and machine learning algorithms are utilized to extract the data characterization, capture the subtle change trends, and recognize the change patterns of multidimensional time series. The proposed model combines both the prior knowledge and data variation characterizations to detect the early signs of the abnormal events. Furthermore, when the events are detected, the model takes the context of the drilling operations, which are automatically calculated in real time, into account to reduce the false alarms.
An early abnormal event detection software tool is built, which is able to detect kick, mud losses and pipe stuck incidents during drilling. The tool used as input both real-time and archived drilling data, and provides alarms when event indicators are detected. More than 50 wells’ historical drill data are used as input to the tool for model verification. The results show that the tool can automatically detect all 25 kick incidents, 4 loss incidents and 21 stuck pipe incidents in the data set. The kick detection time is about 4 mins earlier than the field recorded time by average, the mud losses detection time is about 1 mins earlier by average, and the pipe stuck detection time is about 47 mins earlier by average. The average false alarm rates for kick detection model and stuck pipe detection model is lower than once per 3 hours. The tool was also connected to the real-time drilling data in remote drilling operation support center. During the trail, one kick event and two early stuck pipe signs are detected accurately and timely. The computation time for each real-time data point is less than one second. According to the demonstrated abnormal event detection rate and false alarm rate, the tool is beneficial for detecting kick, mud losses and stuck pipe in early time automatically, which overall improves drilling efficiency and safety.
Comprehensive Assessment on Dynamic Geomechanical Modelling for Fault Re-Active Stress Simulation in Underground Gas Storage
Authors: Chen Dong , Zhou Wei , Wu Yongping , Huang Zhaoting , Li Haiming , Yan Bingxu , Zhu Bo , Feng Xinluo , Huang Xingning , Wu Zangyuan 
Published: February 2025

Abstract
The Tarim Basin, a vast sedimentary basin located in Northwast China. The internal topography of the basin predominantly features uplifted areas to the north, northeast, southeast, and southwest, a gentle slope to the west, and a significant depression in the central region. Cenozoic sedimentary rocks in the Tarim Basin have a cumulative thickness exceeding 6000 meters, with Cretaceous deposits being particularly thick and widespread. The basin's geologic structure is complex and heavily faulted, enriched with geothermal, solar, and mineral resources, hence presenting a favourable environment for inducing seismic activity. Therefore, assessing the stress characteristics and susceptibility to sliding of geological structures in the Tairm Basin holds paramount importance for earthquake mitigation and disaster prevention. This study involved statistical analysis of data from 19 boreholes, 65 hydraulic fracturing experiments, and 44 stress relief measurements from the basin and adjacent areas. The study also discusses fault slip potential and seismic hazards based on fault mechanical theories such as the Byerlee-Anderson theory. Results indicate a shift from compressive (thrust) to transcurrent (strike-slip) stress regimes, aligning with the distribution of high-angle right-lateral NNE-trending reverse faults within the region. The dominant orientation of the maximum horizontal principal stress ranges between N45° and E60°. Preliminary inversion results suggest a primary compressive stress regime with localized strike-slip characteristics, which corroborates the inversion results from focal mechanism studies. The average friction coefficient of the faults in the region is calculated at 0.41, indicating a state of stability and low susceptibility to fault slipping. Additional analyses, interpolating lateral pressure coefficients and stress accumulation indicators, uniformly suggest a low general predisposition for fault slipping, although localized higher levels of stress accumulation are observed in shallow fault zones. Our comprehensive analysis infers that faults are more likely to slip in a NW-SE orientation.
A Systematic Approach to Prevent Casing Deformation in Deep Shale Gas Wells- A Case Study From China
Authors: Zhang Huali , Wang Lei , Shao Yinan , Zhang Ning , Xiong Likun 
Published: February 2025

Abstract
In the Luzhou region of the Sichuan Basin, deep shale gas horizontal wells at depths over 3,500 meters have experienced casing deformation issues during staged fracturing operations. This problem has significantly constrained the development efficiency of deep shale gas in this area. A multi-factor analysis was conducted on typical deep shale gas horizontal wells in the Luzhou block, further clarifying the main characteristics and causes of casing deformation.
Physical simulation analysis of casing deformation during shale gas well fracturing revealed the mechanism behind the casing deformation, providing a theoretical basis for prediction and prevention. It was found that casing deformation in deep horizontal wells in the Luzhou block is primarily influenced by geological and engineering factors. During fracturing, large volumes of fracturing fluid are injected into the formation, and after connecting with natural fractures, the formation exerts shear stress on the wellbore, leading to casing damage.
The results show that in the presence of natural fractures, varying stress conditions can alter the direction of hydraulic fracture propagation. Under strike-slip fault stress conditions, hydraulic fractures are prone to deflection, causing shear failure. The stress state and the inclination of natural fractures are the primary factors influencing the slip and movement of the fracture surfaces. Under strike-slip fault stress conditions, natural fractures are more likely to experience slip and shear, leading to casing deformation. The closer the natural fractures are to the Coulomb failure surface, the more likely they are to slip and displace, causing casing deformation. Further analysis of field wells confirmed the factors contributing to casing deformation, providing technical guidance and experience for the prediction and prevention of casing deformation.
Optimization of Shut-In Time Based on Oil Saturation Rebalancing in Post-Fracturing for Horizontal Wells
Authors: Li Xiang , Zhou Wei , Pu Wei , Xie Lei , Fu Lei , Ji Baoqiang , Li Junfei , Yang Xiao , Huang Xingning , Wu Zangyuan 
Published: February 2025

Abstract
Based on the shut-in imbibition process in low-permeability reservoirs, this paper illustrates the saturation rebalancing principle of post-fracturing well shut-in. It establishes an optimization method for shut-in time aimed at shortening the oil production initiation period and achieving quick oil breakthrough. The study analyzes the effects of permeability, porosity, fracture half-length, and fracturing fluid hydraulic on shut-in time. The results show that during the well shut-in period following hydraulic fracturing, oil and water in the matrix and fractures undergo imbibition displacement. If the shut-in time is too short, the oil-water displacement will be insufficient, leading to a longer oil breakthrough time after production. Conversely, if the shut-in time is too long, despite sufficient oil-water displacement, significant dissipation of formation energy near the wellbore may occur, resulting in a shorter natural flow period and lower production rate. Appropriate shut-in times can reduce the oil breakthrough period, extend the natural flow period, and increase well production. The optimal shut-in time is influenced by factors such as permeability, porosity, fracture half-length, and fracturing fluid hydraulic. The minimum and maximum shut-in times are negatively correlated with porosity, permeability, and fracture half-length, and positively correlated with the hydraulic of fracturing fluid. Practical applications in low-permeability reservoirs in the Junggar Basin confirm that the shut-in time optimization method can effectively enhance the development efficiency of hydraulic fracturing.
Critical Techno-Economical Assessment of Coiled Tubing Gas Lift for Revival of Dead Oil and Gas Wells
Authors: K K. Chanchlani 
Published: February 2025

Abstract
The recompletion of oil wells with an artificial lift system requires a large capital investment in addition to intervention through workover rig with additional issue of liquid fallback increasing with the depth. Coiled Tubing Gas Lift (CTGL) is method to inject gas through coiled tubing with coiled tubing hanger connected to gas injection line. Gas is injected down continuously through a single point (in case of gas wells) or multi-point (in case of oil wells where unloading gas lift valves are desired for proper flowback in case of hydraulically fractured wells) in the coiled tubing which is mixed with oil in production tubing-coiled tubing annulus and helps in lifting oil to the surface. To hang off the coiled tubing in Christmas tree and connect to gas line, tubing hanger and an additional flow tee must be installed above existing flow tee. The objective of this technology is to define the deepest possible injection depth with the available surface gas injection pressure. The critical velocity for continuously removing the liquids by gas lift through coiled tubing and pressure distribution along with annulus for gas-liquid two phase flow are the conditions based on which the CTGL is designed. For reviving the dead oil wells, coiled tubing strings are cut at required depths and connectors are made to accommodate side pocket mandrels on both sides of cut coiled tubing section. Influx problem, hydraulic fractured oil wells, monobore hydraulically fractured wells, liquid loaded wells and wells with casing integrity issues are the candidates for CTGL. Single size CT allows reuse of CT and wellhead equipment in additional wells. The paper will screen out the applicability of this technology in ceased oil and gas wells.
Enhancing Reliability and Emissions Reduction: The Impact of Compact Wide Range Electrical Submersible Pumps
Authors: Saputra M. N. , Rahmanto B. A. , Anggaraini H. , Ryanta A. 
Published: February 2025

Abstract
S-Field stands out as one of Indonesia's largest mature oil fields, boasting a history dating back to its development in 1952. Over the past four years, an average of 450 rig activities annually has been dedicated to repairing and resizing the 1000 Electric Submersible Pumps (ESPs) employed for artificial lift operations. These pumps are crucial for achieving optimal flowrate production, with production targets ranging from 100 to 15,000 Barrels of Fluid per Day (BFPD). However, the extensive rig activity presents significant challenges in managing artificial lift performance, inventory, and energy consumption efficiently.
To address these challenges, the introduction of Compact Wide Range Electric Submersible Pump (CWR ESP) Technology offers a breakthrough solution. This innovative technology enables pumps to operate within an exceptionally wide flowrate range, from 500 to 3000 BFPD. Achieving this remarkable range is made possible through the utilization of high rotational pump speeds, driven by permanent magnet motors, ensuring energy efficiency throughout operation.
In October 2021, a set of CWR ESP D2000HS pumps were deployed, marking a significant milestone. These pumps seamlessly transitioned from conventional speeds of 3000 rpm to an impressive 7000 rpm without encountering any reliability issues. Notably, the CWR ESP demonstrated its capability to produce a flowrate ranging from 600 to 2400 BFPD through periodic speed adjustments alone, eliminating the need for rig intervention. This saved valuable time, preventing three days of potential production loss, and eliminating rig fuel consumption. Impressively, the CWR ESP exhibited reliable performance for over 700 days before proactive replacement was deemed necessary. Comparatively, the tested CWR pump surpassed the median ESP run life at Sinam Field by 104 days and outperformed four conventional ESP types. Additionally, it recorded 8.7% reduction in power consumption compared to conventional ESPs with identical flowrates.
The demonstrated technical prowess and reliability of CWR ESPs present a compelling alternative for artificial lift operations. Beyond enhancing operational efficiency and reducing carbon emissions through rig optimization and energy-efficient operations, the CWR's benefits extend to inventory rationalization, particularly in large, mature field operations.
Overcoming Dysfunctions from Drilling Interbedded and Hard Rocks and Improving Drilling Efficiency
Authors: Centala P. , Suleiman A. 
Published: February 2025

Abstract
This paper shares the learnings from laboratory testing and field testing of a multi-faceted polycrystalline diamond compact (PCD) cutter that can enhance the impact load resistance and toughness significantly up to 60% when compared to a conventional round cutter. Another concept presented is a secondary cutting element's placement to support the primary cutting structure in overcoming shock loads while drilling interbedded formations. Both technologies help overcome shock load dysfunctions in drilling interbedded applications and nodular chert lithologies while maintaining cutting structure integrity, resulting in improved drilling efficiency.
A systematic study was conducted to understand how to enhance the underlying cutter strength by varying the geometry of the diamond table. Different loading methods were used to simulate static, dynamic, and impact loads on the various designed shaped cutter geometries. The laboratory-winning design was then tested on several bit designs for hard rock and geothermal applications where fixed cutter bits could not drill for long intervals.
The lab-simulated drilling tests suggested that the sensitivity of these cutter placements on sections of the bit profile and field trial bit designs in both vertical and lateral sections demonstrated performance improvements in the range of 20% to 40%. Bit durability, footage, and rate of penetration (ROP) were assessed systematically. Multi-faceted cutters provided the benefits of supporting the overall cutting structure integrity while drilling very hard formations and interbedded lithologies. The multi-faceted cutter has an intricate rock interacting geometry capable of withstanding high reactive drilling forces. These niche shaped rock removal elements avoid premature failure and mitigate the onset of bit dysfunctions.
The case studies presented clearly demonstrate how these cutters can overcome performance limiters, bring about drilling cost savings, reduce the number of trips, and minimize damage beyond repair (DBR) of bit bodies. Impact test results revealed that the optimized multi-faceted cutter and the secondary element showed clear dominance over conventional cutters.