bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wettability Alteration with Weak Acid-Assisted Surfactant Flood
Authors: Shi Yue , Niu Fangya , Mohanty Kishore 
Published: March 2023

Summary
Oil-wetness and heterogeneity are two key reasons for low oil recovery by waterflooding in carbonate reservoirs. Surfactants have been effective in altering the oil-wet matrix to a more water-wet condition and initiating spontaneous imbibition. Because it takes time for the surfactant to alter wettability, oil recovery from the tight matrix is slow and sometimes not economically feasible. Acids have the potential of dissolving minerals, which may alter wettability. In this study, the enhanced oil recovery (EOR) performance of an acid-assisted surfactant solution, a novel technique, was evaluated for low-temperature applications. A set of acids and their acetates were tested. Bulk rock-acid reaction, wettability alteration (WA) tests, and spontaneous imbibition measurements were conducted at reservoir temperature (35°C) to identify effective candidates. Coreflood tests were then performed to evaluate the selected acid-surfactant formulations. Before and after a coreflood test, the core was scanned using micro-computed tomography (CT) to investigate pore structure alteration. Bulk reaction measurements showed that weak acids, especially acetic acid (AA), have the desired low reaction rates at 35°C. WA tests showed that AA can remove the crude oil off the rock surface and alter wettability through mineral dissolution. The surfactant can reduce contact angles from 160° to 58°; adding acid into the surfactant can further reduce it to 52°. Spontaneous imbibition experiments showed the synergy between the acid and the surfactant; the AA-surfactant solution had the highest oil recovery (62.6%) among acid-surfactant formulations. The acid improves the WA efficiency by the surfactant through surface mineral dissolution and lower ζ-potential. The imbibition transports the acid-surfactant solutions into the matrix, which minimizes face dissolution. Coreflood tests show that the AA-surfactant flood can increase the oil recovery rate and recover about 8% more oil compared to the surfactant flood. Micro-CT showed that a few mineral particles were transported along the core and partially plugged pore throats, which reduced permeability and diverted flow leading to improved oil recovery. The transport of the acid in reservoirs and the potential plugging issues have to be carefully evaluated in future studies.
Integrated Velocity Modeling by Water Table Imaging and Structural Smoothing in Yingxiongling, Qaidam Basin
Authors: Tan Chenqing , Wang Yongsheng , Tong Yanming , Ou Rongsheng , Wu Chuan , Yan Yufei , Zhao Changlei , Li Xiang , Cui Jie , Dong Yongcang , Li Rong 
Published: March 2023

AbstractThe Yingxiongling structural belt is located in the south of world's highest-altitude petroliferous basin, Qaidam Basin. It is well known for the extremely complicated topography and subsurface structure. Accurate velocity modeling and depth imaging is extremely difficult, as well as exploration and production in this area. Building a reliable initial model that accounts for both near-surface and subsurface structures is crucial. We first generate a geologically-guided subsurface velocity model by structural smoothing of the pre-stack time migration (PSTM) velocity guided by dip field. Furthermore, we take the water table, a typical geological phenomenon in Qaidam basin, into account for near surface modeling. With information regarding a stable and smooth water table, we achieve an optimum image predicting the trap, thus supporting exploration and production in the area.
True Single-Trip Wellbore Cleanout: Optimizations in Cemented Liner and Multi-Stage Frac Completions
Authors: Franco Nata , Cardoso Luiz Miguel , Corona Mauricio 
Published: March 2023

Abstract
Depending on the production requirements, the deep gas wells in the field were completed with cemented liner or multi-stage frac equipment. Following installation of lower completion, these wells historically required 3 to 4 wellbore cleanout runs prior to deployment of upper completion equipment. This paper will describe the optimizations done to convert all the cleanout runs, into a true single-trip job, reducing the total well construction by introducing groundbreaking technology and fit-for-purpose operations.
The standard procedure wellbore cleanout involved 3 to 4 trips: Firstly, cement cleaning was done inside the 4-1/2″ liner, including drill-out of shoe-track, followed by scraping of 7″ liner for running test packer tool; then run and setting of packer to perform casing and top of liner pressure tests; next perform full cleanout of casings, pickle production casings and displacing well to brine, and finally polish 4-1/2″ liner tie-back receptacle to receive upper completion assembly in cemented applications. Detailed engineering analysis, risk assessment and market research were conducted to develop an optimized wellbore cleanout assembly, to perform single-trip jobs.
The conventional cleanout package was upgraded with modified scrapers, magnets, and brushes, and combined with specialized high-pressure test packer and polish mill. Modification in equipment and procedures evolved following results and observations of several runs of the combined technology. The drilling and completion fluids were also re-engineered to ensure proper cleaning of casing and free-solids wellbore. The final results were an extreme success and single-trip wellbore cleanout became the new norm in the project. The innovate approach greatly contributed to reducing the number of runs to prepare the wellbore for upper completions.
Operations have been conducted safely throughout its implementation and kept at low non-productive rate. In average, the reduction of total well time was 3.5 days with relatively marginal tool rental cost increment. This optimization was a breakthrough in the Middle East with major rig time savings and it will serve as a reference for other operators and service providers to achieve step changes in similar operations. The key elements of this initiative will be described in detail in the paper.
Gas Lift Application for Oil Wells with Heavy Crude, Thirty Years of Operation Offshore Gulf of Suez
Authors: Korish Mahmoud Ismail , Elwan Mahmoud Attia , Mousa Hisham Elsaied , Shahin Eman Said , Ibrahim Mohamed Elsayed 
Published: March 2023

Abstract
This paper presents the implications of Gas lift over the heavy oil fields, since Gas Lift is considered one of the oldest artificial lift techniques in Oil industry. Despite the numerous publications about different aspects of gas lift, few of them is meant to deeply consider the applicability of gas lift to heavy oil production. Gas Lift has been applied to heavy oil in different places around the world. For Gas lift has been used in Gulf of Suez in Egypt historically to produce Heavy Oil Reservoir with 17 – 19.5 API.
The major challenge for application of Gas lift in heavy oil application is the typical low GOR encountered in Heavy oil fluid properties. The low GOR may not be suitable for gas supply to compressors, which requires gas availability to avoid tripping due to low suction or overheating during startup operations. However, in many cases nearby gas wells has been used as gas supply to compression equipment used for gas lift.
Elevating Drilling Performance & Efficiency to Highest Levels in Field A – Journey from 150 to 31 Drilling Days
Authors: Ullah Safi , Ashraf Muhammad Sajjad , Ahmed Ali Mohiuddin , Ahmad Daniyal , Haider Mohammad Murad , Usmani Mohammad Mohsin , Ali Syed Dost 
Published: March 2023

Abstract
Field A is one of the most challenging fields in the Potowar region of Northern Pakistan with severe problems of fluid loss, high-pressure shallow water influx, low drillability, clay reactivity/ shale instability and depleted reservoir sections. This paper gives a brief overview of the methods and changes made along with results achieved, enabling the well to reach total depth in just 31 days compared to an average of 150 days taken on offset wells.
Due to severe drilling challenges, the wells were drilled in six-hole sections starting with 36″ surface hole. An entirely new well engineering strategy has been utilized to enhance the drilling performance in the last five wells drilled in the field. Some of the major areas of change include Customized bit design, BHA and hydraulics design, casing design optimization and change in casing seat strategy as well as novel changes in drilling fluid design and selection of Loss Control Material.
Dysfunctions and limiters in drilling which were affecting the hole cleaning, mechanical specific energy (MSE), hydraulics efficiency, and ROP were eliminated.
A detailed analysis of the impact of changes in bits and bottom hole assembly design, drilling fluids design, and casing design is shared in the study for the last fifteen wells drilled in the field. Continuous learning and enhancements in all the subject areas are analyzed with respect to the use of different strategies and technologies. An analysis has been performed for non-productive time, its root cause and successful actions taken to reduce its occurrence. A huge reduction in drilling time, cost and risks have been achieved as a result of mentioned changes in the latest well setting a benchmark in the entire region. Dry hole time for the last well has been reduced by 78 %, while 65% cost reduction is achieved as compared to the previous average time and cost respectively. After removing the dysfunctions / limiters; ROP enhancement of 5 to 10 times has been achieved in different hole sections.
The learning and experience from the use of discussed technologies and drilling practices can be helpful for optimizing challenging wells with the problems of pressure reversals, drilling fluids losses, well control, drillability issues in gumbo clay/ shales and wellbore stability.
Pinpointing Source of Sustained High Casing Head Pressure (HCHP) for Well Integrity Restoration: A Case Study of a Well in the Niger Delta
Authors: Bougha Arthur , Oluleye John , Ivrogbo Daniel , Okonkwo Ngozi 
Published: March 2023

AbstractMaintaining the integrity of oil and gas wells is of utmost importance. This requires regular monitoring to ensure the barrier envelop is maintained. Sustained pressure in the casing infers a compromised barrier envelop. It poses a serious threat to the well integrity and if not addressed could lead to increased risk of pressure transmission and fluid leakage through the concentric tubulars. The key objective is the ability to accurately pinpoint the source of the pressure.Modern technologies using through-tubing logging systems are more accurate for leak detection. If the leak is not accurately detected, the sustained high casing head pressure persists and could lead to undesired outcomes even after the repairs. Here, the high accuracy Sonic-Noise Log (SNL-HPT) was deployed through slickline. Data acquisition process involved both shut-in and flowing modes. The shut-in mode required the well to be stable while RIH SNL-HPT tools on slickline for data acquisition. While in the bleed off mode, the well was being produced during data acquisition. A surface choke manifold and flowback tank were rigged-up for flow control.In this paper the results of well Unut-4 Sonic Noise Log- High Pressure and Temperature (SNL-HPT) surveys are presented. The objective was to investigate the source of A annulus pressure in this well. The data was successfully acquired in memory via slickline up to a depth of 10,000ftah using both shut-in and bleed off (flowing) modes. The shut-in mode required the well to be stable while RIH SNL-HPT tools on slickline for data acquisition. While in the bleed off mode, the well was being produced during data acquisition. The acquired data was successfully downloaded and interpreted for the source of leak. The SNL-HPT interpreted data indicated that the High CHP was caused by communication observed through leaks at depth 9,751ft (the dual packer). The spectral noise logging located the active leak source and verified the integrity of cement barriers while the High temperature logging quantified the leak rate using temperature modelling. This paper would detail the history of the well, planning, design and execution of the successful logging including the interpreted results.Sonic Noise Log is a simple technology to deploy for accurate leak source determination. In all the instances this was deployed, acquired and interpreted data was good enough for a decision making on the forward plan. The results of this logging led to the early injection of the well in the rig sequence and well was subsequently worked over. Integrity was restored with further deferment of production averted.
Maximizing Recovery and Reducing Well Cost Using Herringbone Multilateral Horizontal Well Drilling and Completion Technology
Authors: Zhang Xiaocheng , Xie Tao , Huo Hongbo , He Ruibing , Lin Hai , Hou Xinxin , Xu Dongsheng 
Published: March 2023

AbstractWith the in-depth development of Bohai Oilfield, China National Offshore Oil Corporation (CNOOC), the water cut of some old wells become too high to produce while nearby remaining recoverable reserves are still considerable. In order to maximize recovery and reduce well construction cost, herringbone multilateral horizontal well drilling and completion technology is employed to increase drainage area of single well and make full use of well slot and old wellbore.Considering the current development of oilfield and the geological characteristics of reservoir, the technical difficulties of herringbone multilateral horizontal well drilling and completion technology including high build-up rate, easy blockage of drilling tools in the sidetracking in open hole, easy collapse and instability of sandwich wall and high requirements for drilling fluid performance are analyzed and solved.This technology has been successfully applied in three wells with total 6 branches and the production of three wells is twice higher than that of conventional horizontal wells with no water cut, which fully verified the reliability of the branch well tools and the feasibility of the technology.Herringbone multilateral horizontal well drilling and completion technology provides a new idea for the treatment of low production and low efficiency wells in a sustainable way and will be widely promoted and applied in Bohai oilfield, which can also provide reference for other high water cut oilfields.
Water Production Diagnostics and Formation Evaluation to Maximize Workover Profitability of ESP Oil Producers Using Electrical Coiled Tubing, Gulf of Suez, Egypt
Authors: Ghonim Ahmed ElSayed , El-Farran Amr Zienhim , Atef Ahmed , El-Abasy Mohamed , Haridy Ehab , Aboeleneein Mohamed Mamdouh , Abdulaziz Sameh Mohamed Hashim , Mohamed Sara Omar 
Published: March 2023

AbstractWell intervention in highly deviated sour oil wells operating with Electrical Submersible Pump (ESP) completions have always been challenging for well intervention operations due to the restrictions in the wellbore. Workover operations in such harsh environments involve several operational risks and high related costs. Electrical Coiled Tubing (E-CT) equipped with tubing encapsulated mono-conductor cable was used to gather accurate intervention data with real-time logging capabilities. The system used didn't require the temporary installation of a test ESP completion string after pulling the failed ESP pump, saving cost, overall intervention time, optimizing zonal isolation for the water producing intervals, and increasing well recovery in these oil wells.This case study presents a challenging workover for a mature field where E-CT was used to convey a combination of Pulsed Neutron Logging (PNLT) and Production Logging Tools (PLT) while pumping Nitrogen (N2) to lift the well. This enabled maximizing the reservoir production potential while monitoring the dynamic drawdown being applied to overcome the masking potential for the PNLT due to killing operations during workover. Real-time readings from the PNLT, PLT continuous spinners, gamma-ray, pressure, and temperature sensors accurately identified the well's water contributing intervals and flow profile. This accurate interpretation of the water saturation profile across the reservoir was then used for optimum reservoir management and selective zonal isolation. Dynamic wellbore modeling software was used to design the lifting and logging operations for optimal operational efficiency and to increase oil production and reduce water production.Deployment of E-CT in such a harsh environment was challenging in terms of operational execution to ensure safe conveyance of the real-time logging tools while performing the conventional lifting of the well. Intervention time was optimized through two runs to evaluate the formation performance and water saturation profile before isolating the water-producing intervals.Such utilization of E-CT allowed accurate formation evaluation, water saturation profiling, and nitrogen lifting of the well resulting in an optimal intervention. Results showed a 50% reduction in water production and an increasing well potential from the upper intervals. Total workover and intervention costs were reduced dramatically compared to other treatment options for water production problems with potential workover complications and deferred production.
Novel Approach to Identify Sand and Viscous Oil Problems Through the Analysis of Dynamometer Cards and Field Practices
Authors: Chanchlani Kuldeep , Gunwant Deepak , Gogoi Ranjit , Singh Kamal , Dadhich Jeetendra , Rajak Himanshu 
Published: March 2023

AbstractProblems due to the solids and viscous oil are difficult to predict in the dynamometer cards. An innovative approach is devised to identify solids and viscous oil problems, based on the interpretation of dynamometer card analysis and troubleshooting practices implemented at the field scale. Sand or wax incursion in the subsurface pump causes the pump screen or perforation to choke, resulting in no communication of the reservoir with the tubing. It can cause no free fall of polished rod and sucker rod string getting stuck up. Heavy viscous reservoir fluid shows the standing valve, traveling valve, or both pump seats getting choked. The drag force creates an extra differential force between the plunger and the pump, showing the case of the sucker rod unscrewing or parted as pump seats get choked up in the dynamometer card.Casing head pressure, pump hydraulics, and the shape of the dynamometer card are critical parameters in differentiating between the fluid pound, gas interference, and blocked pump intake. The plunger stops before opening the traveling valve in case of pump intake is blocked, or the spiky and curvy loads in the dynamometer card due to solids-related problems. During the circulation job, higher pumping pressure taken by the pumping unit ascertains the solids incursion. Viscosity is an important property that determines load distribution on the rod string. The drag force causes the dynamometer card to stretch, but practically the rod is unscrewed or parted. Post-rod string makeup well started producing liquid. It has revived non-flowing wells and prevented production downtime. This unique approach will benefit the operators in analyzing the sand, solids, and viscosity-related problems and troubleshooting these failures of rod-pumped wells. Oil gain has been observed in rod-pumped wells based on this systematic approach.
Challenges of Drilling Deep Wells in a Complex Overburden with Severe Depletion and Experiences From Caspian Sea
Authors: Al Saadi Anwar Juma , Naidu Rajarajan Narayanasamy 
Published: March 2023

AbstractThe objective of this paper is to share Dragon Oil's experience to overcome challenges in drilling deep depleted reservoirs in the Cheleken Contract Area, Caspian Sea, Turkmenistan. Dragon Oil operates two producing oilfields; Lam and Zhdanov. The main targets described in this paper are from the Zhadanov field with the deepest target reaching around 4000m. This paper describes the challenges and experience from drilling complex wells in this area.The wells described in this paper penetrate various depleted reservoirs due to past production. The deepest reservoir consists of a sequence of interbedded sands with varying pore pressure due to geology and depletion due to production. The intra-reservoir shale layers are unstable and require high Mud Weights, often reaching technical limits (up to 20 ppg).The requirement of high mud weight to address shale instability is in contrast with the solutions for drilling depleted sand and the common drilling risks are mud losses and stuck pipe. An analysis of challenges, risk mitigations and lessons learned are discussed in this paper.Drilling a deep 6" directional hole is challenging and it requires continuous monitoring of the drilling fluid density. The pre-drill well planning is a key solution for preparing to deal with operational challenges and develop a strategy for reducing risk. This paper describes the important steps followed in the well planning process, risk mitigation options analyzed and incorporating the key elements in drilling program to overcome challenges.Some of the lessons learned from the experience of delivering wells in such complex area are: Implement 3D/4D PPFG and wellbore stability models to communicate depletion magnitudes accurately and effectively incorporate the risk in well planning to enable drilling with minimum overbalance.Map the correlation between depleted sand bodies (e.g. facies model) and assess impact of fault typesImplement Synthetic Oil Based Mud to improve wellbore condition and enhance drilling performance.Choose well trajectories to help transfer weight/torque to bottomMinimize the BHA static time across severely depleted zonesThis paper shares the experience from Turkmenistan and lessons learned from Dragon Oil's operations in Caspian Sea. This paper consolidates the well planning process, methods adopted to incorporate risk mitigation into drilling program and our recent experience from drilling complex wells targeting deep depleted reservoirs.
Research on Pore Pressure Prediction Technology of HTHP Wells in South China Sea Based on Machine Learning
Authors: Xu Dongsheng , Yang Jin , Zhao Yuhang , Fan Jianchun , Li Yanjun , Liu Xun , Chen Kejin , Song Zehua , Zhang Xun , Zhu Hong 
Published: March 2023

Abstract
The Yingqiong Basin in the South China Sea is located at the intersection of the Eurasian and Indo-Chinese plates, with complex geology and often accompanied by abnormally high pressure. In this paper, we analyze the causes of anomalous high pressure in the South China Sea and analyze the commonly used machine learning methods, support vector machine and BP neural network, and use both methods to predict a block in Yingqiong Basin. The field application was carried out using this method, and the application showed that the prediction accuracy exceeded 95%, the complexity was reduced by 42%, and the drilling efficiency was improved by more than 53%, which played a good guiding effect to the field.