bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Dual-Tubing Technique to Eliminate the Shut-in Period in CO2 Huff-n-Puff Injection for Heavy Oil Carbonate Reservoirs
Authors: Hamdi Zakaria , Mohanadas Nirmal , Lilaysromant Margarita , Talabi Oluwole 
Published: June 2021

Abstract
Some heavy oil production can be established using conventional methods; however, these methods are often somewhat ineffective with low recovery factors of less than 20%. Carbon dioxide (CO2) huff-n-puff or cyclic CO2 injection is one of the Enhanced oil recovery (EOR) methods that can be used in stimulating aging wells to recover some residual oil. The shut-in stage of this method results in a significant delay in the production time, and hence lower oil recovery. For the first time, in this paper, an attempt is made to overcome this issue by a novel approach, employing dual tubing completions. The aim of this is to increase the oil recovery with the production during soak time. Also, a majority of the remaining heavy oil reservoirs are carbonates, hence the research was focused on the same conditions. Numerical simulation is done using dual-tubing conditions in a dual-porosity model with conventional tubing as a base case. Optimization studies are done for injection rate, injection time, soaking time, production time, and huff-n-puff cycles. The results show that the recovery factor can increase significantly, with no discontinuity in production. Preliminary economic studies for the cases also showed a net increase in profit of 7% (1.3 million Dollars for the case chosen). This demonstrates the feasibility of the proposed method which can be implemented into conventional operations, for a more sustainable economy in the era of low oil prices.
Automatic Identification of Rock Formation Type While Drilling Using Machine Learning Based Data-Driven Models
Authors: Z. Losoya Enrique , Vishnumolakala Narendra , Noynaert Samuel F. , Medina-Cetina Zenon , Bukkapatnam Satish , Gildin Eduardo 
Published: June 2021

Abstract
The objective of this study is to present a novel rock formation identification model using a data-driven modeling approach. This study explores the use of real-time drilling data to train and validate a classification model to improve the efficiency of the drilling process by reducing Mechanical Specific Energy (MSE). In this study, we demonstrate the feasibility of a layer-based determination and change detection of properties of rock formation currently being drilled as accurately and fast as possible. Data for this study was collected from a custom-built lab-scale drilling rig equipped with multiple sensors. The experiment was conducted by drilling through an arrangement of different rock formations of varying rock strength properties. Data was recorded and stored at a frequency of 2 kHz, then filtered, processed, and downsampled to extract relevant features. This dataset was used to train an Artificial Neural Network and other machine learning classification algorithms. Feature selection was made first with ten most notable features found by Random Forest, and the second set with derived measurements and down-sampled dynamic features from the sensors. The classification analysis was divided into two steps: the best predictors/features extraction and classification model building. The models were trained using multiple classification algorithms, namely logistic regression, linear discriminant analysis (LDA), Support Vector Machines (SVM), Random Forest (RF), and Artificial Neural Networks (ANN). It was found that random forest and ANN performed the best with prediction accuracy of 99.48% and 99.58%, respectively, for the data set with ten most prominent features. The high prediction rate accuracy for the most prominent predictors suggests that if the high-frequency data can be processed in real-time, predicting what formation we are drilling in is possible to achieve in near real-time. This can lead to significant savings for drilling companies as optimal drilling parameters can be computed, and in turn, optimized Mechanical Specific Energy can be obtained in real-time. Since the rock formation identification is time-consuming, we also describe here an alternative approach using slightly less accurate but equally powerful dynamic predictors. In this case, we show that our dynamic predictor models with RF and ANN yielded prediction accuracy of 96.30% and 95.61%, respectively. Both the prominent feature and dynamic predictor approaches are described in detail in this paper. Our results suggest that accurately predicting rock formation type in real-time while drilling is very much feasible with lesser computational cost and complexity. This study provides the building blocks for the development of a completely autonomous downhole device and Electronic Device Recorders (EDR) that reduces the need for highly sophisticated sensors or data transmission processes downhole.
First Implementation of an Innovative Mud-Removal Solution to Improve Well Integrity in Egypt
Authors: Abdulaal Ahmed , El Nadoury Mohamed , Pallapothu Surya , Mohamed Fayed , Younan Joseph , Sabra Yasser 
Published: June 2021

Abstract
Downhole well integrity starts by removing the drilling fluids from the well and cleaning the annulus using a spacer to prepare for the cement to be placed. The Kamose field in the Egyptian Mediterranean Sea is drilled with a diesel oil-based drilling fluid system that is very difficult to remove with conventional spacer technologies. To improve the mud removal, an innovative spacer based on fiber scrubbing technology was used successfully.
The Kamose wells are drilled with high deviation that varies from 60˚to75˚ resulting in poor mud removal due to insufficient casing standoff. The narrow windows between pore pressure and fracture gradients limits the pump rate and thus results in the unsuccessful use of conventional spacers. This results in a mud layer that is always left in the narrow side of the well, which impacts the log response and the downhole well integrity. To address the issue, an innovative mud removal solution was developed. The spacer design includes an engineered scrubbing material which, through mechanical action, cleans the surfaces of the casing and the formation. This allows for better contact of the cement with the casing, formation surfaces, and bonding.
Extensive laboratory qualification tests with the current drilling fluids were performed not only to check the cleaning efficiency of the new spacer but also on the compatibility with all the other fluids. The results show a very high cleaning efficiency of 90% compared to 68% when using a conventional spacer. The solution was combined with the local cementing best practices which produced an excellent log response using sonic and ultrasonic tools therefore ensuing the downhole well integrity.
The case history of the spacer fiber-based technology solution provides an alternative to improve the cement bond evaluation and ensuring downhole well integrity.
Leveraging on Machine Learning Solution for Pioneering Wells Augmented Stuck Pipe Indicator in Real Time Centre
Authors: Yusoff Mohamad Hazwan , Meor Hashim Meor Muhammad Hakeem , Hamzah Muhammad Hadi , Arriffin Muhammad Faris , Mohamad Azlan 
Published: June 2021

Abstract
Stuck pipe incidents remain as one of the major problems in the drilling industry. The incidents will lead to expensive loss time in daily spread cost, bottom hole assembly cost, sidetracking cost as well as fishing cost. The Wells Augmented Stuck Pipe (WASP) Indicator, a state-of-the-art machine learning technology that seamlessly integrates with PETRONAS existing technologies, is introduced as the stuck pipe prevention detection system for the company. Historical real-time drilling data and stuck pipe incidents reports between 2007 and 2019 are used for the development of machine learning models. The models utilize key drilling parameters such as hookload and equivalent circulating density (ECD) to predict and analyze trends to detect any signature pattern anomalies for various stuck pipe events. The prediction and alarm are displayed in real-time monitoring software to trigger the operation team for prompt intervention. The WASP solution has demonstrated proven outcomes using historical and live well with high confidence in detecting stuck pipe incidents due to differential sticking, hole cleaning, and wellbore geometry. The WASP Indicator is envisaged to provide the company with cutting edge advantages in the industry. It is expected that the system will reduce the identification period and improve the reaction time of the monitoring specialists in recognizing the stuck pipe symptoms and highlighting potential incidents. The system is also bringing value to the company via non-productive time (NPT) cost avoidance and identification of early onset of various stuck pipe events based on distinct mechanisms. With the system, the existing portfolio value can be enhanced via setting dynamic trends and models into historical experiences context. The WASP Indicator is aspired to be the forefront innovation that will leap through the norm and lead the region in a greater plan of drilling automation system.
A New Cationic Shale Inhibitor and Water Blocking Agent for Water-Based Drilling Fluid
Authors: Al-Heed Mohammed , Murtaza Mobeen , Hussain Sayed , Gajbhiye Rahul 
Published: June 2021

Abstract
Drilling a shale formation is one of the challenges faced by the petroleum industry. Designing the drilling fluid, that reduces the interaction with shale, is important for safe and efficient drilling. This study investigates the new cationic surfactant as a shale inhibitor for the drilling fluid. The main objective of this study is to block the water penetration into the clay layers using the new shale inhibitor and evaluate its performance with commercial shale inhibitors.
To assess the performance of new cationic surfactant two reliable clay sources were considered. The first source is from unconventional Qusiba (Kaolinite) formation in Saudi Arabia and the second is a commercial Bentonite. The effect of new cationic formulation on preventing clay swelling were tested using API dynamic swelling meter at reservoir condition.
Further, X-ray diffraction and SEM analysis were performed to ensure clay stability before exposing it to WBM and after exposure for cation exchange phenomenon, shape and size of the particle and efficacy of water penetration blockage. The results were also compared with commercial shale inhibitor.
The results show that the new cationic surfactant can act as a shale inhibitor as well as water blocking agent. It also showed acceptable performance compare with common shale inhibitors used in the industry, the performance can be further improved by optimizing the percentage of surfactant addition to the drilling fluid. This study provides the new cationic surfactant and proved to have good feature for oilfield applications and the cationity which is helping to reduce the water shale interactions.
A New Re-Fracturing Candidate Selection Method for Multi-Fractured Horizontal Well in Tight Oil Reservoirs
Authors: Tao Liang , Zhang Xiaozhuo , Yang Shubo , Xian Sheng , Zhao Yuhang , Zhao Zhihong 
Published: June 2021

Abstract
The selection of refracturing candidate is the primary challenge of refracturing technology. There are many factors affecting the selection of refracturing candidate for multi-fractured horizontal wells (MFHWs) and the relationship between each factor is very complicated, which makes it very difficult to select the optimal wells. A new method combining initial completion efficiency and production performance was proposed in this study to solve this problem. First, the fracture parameters were obtained by fitting method to evaluate the initial completion efficiency. Then, the geological model was established by the method of reservoir numerical simulation to evaluate the dynamic effect of production. Finally, the potential of refracturing was evaluated. The new method has been successfully applied to 30 wells of the tight oil reservoirs in Songliao Basin China. The average daily oil production was 18.5 tons/day after refracturing treatment. This research could provide significant guidance for the development of tight oil reservoirs.
A Spectacular Cementing Record in Myanmar Offshore Deepwater Well
Authors: Sun Gang , Ullah Mohammad Solim , Li Yi , Maheshwari Mukesh , Khumtong Thirayu , Xiong Shao Chun , Ai Wu Chang , Balaraman Balasundaram , Edward Mic Mac , Chen Feng , Yao De Gang 
Published: June 2021

Abstract
Myanmar offshore is considered to be a very promising exploration and production (E&P) location for oil and gas but poses significant challenges to drilling and cementing operations. Low temperature at sea bed delays the cement compressive strength development, High pore pressure with steep gradient and low fracture pressure created a very narrow drilling margin, presence of shallow flow in riser-less section further complicated the cementing operation, low density cement with high performance is a must. With the exorbiant cost of Deepwater drilling, much needed fit for purpose cementing technology with efficient logistic support and excellence in execution became crucial.
This paper elaborates the cementing challenges at different sections of a recent deep-water well in offshore Mynamar and techniques that were planned and used to address those challenges. This paper will describe in detail the cementing method, how it fit the well situation, how the cement slurry was designed then evaluated and how the logistic support and execution were carried out, resulting in a resounding success.
Valuable Cuttings-Based Petrophysic Analysis Successfully Reduces Drilling Risk in HPHT Formations
Authors: Chen Jianlin , Yao Yanhua , Liu Yingbiao , Wang Zhaofei , Collier Craig , Tang Wenhuan 
Published: June 2021

Abstract
Cuttings data has always been neglected or forgotten as a source of information by many operators. In some areas, it is even common practice to throw away cuttings in order to reduce cost. However, cuttings data can yield a great amout of information to provide great value and support to drilling operations, as well as reduce potential downhole risks. This was evident in wells drilled in remote Western regions of China, where wells typically have high temperature high pressure (HTHP) formations with a true vertical depth ranging between 4000-7000 meters and target formation temperature between 150-160 degrees Celcius.
Due to severe drilling conditions, the measurement tools of Logging While Drilling (LWD) and Measured While Drilling (MWD) are at high risk of running into holes. Even due to the high formations’ temperatures is over the bottom line of LWD and MWD tools, the sensors of LWD and MWD cannot work efficiently in such circumstances, increasing the drilling risk and expense. Thus, "blind" drilling is the most reasonable economical choice for local operators. Without sufficient real-time formations’ information, the drilling uncertainties dramatically increase. The fluid loss, pipe stuck, as well as drilling bit damages frequently occur. Currently, there is no successful well that accesses to the target reservoir. The data from the wireline logs and cores cannot be available, as the well is the first exploration well in the block; however, during drilling, only drill cuttings are available for peoples.
The creative cutting-based petrophysics models are built for the formation analysis that is able to provide rock density, cuttings gamma, Delta Time of Compressional Acoustic (DTC), Unconfined Compressional Strength (UCS) Index, Caliper Index, Brittleness Index, and Hydrocarbon Index from the cuttings samples at the wellsite on a near-real-time basis. This data can help people quantitatively and qualitatively evaluate the downhole formations on a near-real-time basis and can help people to make a more reasonable decision, and therefore, reduce the drilling risk within a controlled level. The authors provide the several cases to study the cutting models into drilling events, and proves the models are consistent with log and core data, and match the drilling parameters and like ROP, and pumping pressure, as well as torque, and bit performance. LWD and MWD are unable to run into the hole due to high formation pressure and extreme risky hole. The field portable XRF instrument is applied, and the mineralogy and elements input into the models. The cuttings petrophysics analysis application can provide the valuable information for drilling engineers to drill the wells to TD.
Obtaining Zonal Isolation in Geothermal Wells
Authors: Rachimillah Allam Putra , Azwar Cinto , Johri Ambuj , Osman Ahmed , Tanoto Eric 
Published: June 2021

Abstract
Cementing is one of the sequences in the drilling operations to isolate different geological zones and provide integrity for the life of the well. As compared with oil and gas wells, geothermal wells have unique challenges for cementing operations. Robust cementing design and appropriate best practices during the cementing operations are needed to achieve cementing objectives in geothermal wells.
Primary cementing in geothermal wells generally relies on a few conventional methods: long string, liner-tieback, and two-stage methods. Each has challenges for primary cementing that will be analyzed, compared, and discussed in detail.
Geothermal wells pose challenges of low fracture gradients and massive lost circulation due to numerous fractures, which often lead to a need for remedial cementing jobs such as squeeze cementing and lost circulation plugs. Special considerations for remedial cementing in geothermal wells are also discussed here.
Primary cement design is critical to ensure long-term integrity of a geothermal well. The cement sheath must be able to withstand pressure and temperature cycles when steam is produced and resist corrosive reservoir fluids due to the presence of H2S and CO2. Any fluid trapped within the casing-casing annulus poses a risk of casing collapse due to expansion under high temperatures encountered during the production phase. With the high heating rate of the geothermal well, temperature prediction plays an important part in cement design. Free fluid sensitivity test and centralizer selection also play an important role in avoiding mud channeling as well as preventing the development of fluid pockets. Analysis and comparison of every method is described in detail to enable readers to choose the best approach.
Massive lost circulation is very common in surface and intermediate sections of geothermal wells. On numerous occasions, treatment with conventional lost-circulation material (LCM) was unable to cure the losses, resulting in the placement of multiple cement plugs. An improved lost circulation plug design and execution method are introduced to control massive losses in a geothermal environment. In addition, the paper will present operational best practices and lessons learned from the authors’ experience with cementing in geothermal wells in Indonesia.
Geothermal wells can be constructed in different ways by different operators. In light of this, an analysis of different cementing approaches has been conducted to ensure robust cement design and a fit-for-purpose cementing method. This paper will discuss the cementing design, equipment, recommendations, and best available practices for excellence in operational execution to achieve optimal long-life zonal isolation for a geothermal well.
Integrated Workflow for Feasibility Study of Cuttings Reinjection Based on 3D Geomechanics Analysis and Case Study
Authors: Shen Xinpu 
Published: June 2021

Abstract
This paper presents an integrated workflow for feasibility study of cuttings reinjection (CRI) based on 3D geomechanics analysis. Solutions of various mechanical variables obtained with 3D geomechanics analysis at various level of scale are used as basis for designing parameters of CRI. Solutions of geomechanics analysis provide basis for a feasibility study and/or design of CRI: solution of 3D geostress distribution and the effective stress ratio are the essential factors for selecting the best location of injection well; solution of 1D geomechanics analysis provides basis for choice of true vertical depth (TVD) interval for injection sections; and hydraulic fracturing performed in the framework of 3D geomechanics analysis provides the most accurate solution for both the injection pressure window and fault reactivation related to CRI as well as estimation of seismic behavior. Example of feasibility study of cuttings reinjection with the integrated workflow proposed here is presented with data from a case in offshore West Africa. Solutions of geomechanics analysis are used for decision making at various stages of CRI. There are several faults in this region. The location of the injection well is chosen at a place with principal stress ratio's value at 0.68. The interval of injection well section is chosen as a 140-ft section with center at TVD = 6,700 ft. The numerical solution of injection pressure window is defined with 46 MPa as lower bound and 80 MPa as upper bound. The width of the fracture is 0.069 m, and length and height are 4,000 m and 100 m respectively. The accommodation volume of fluid with cuttings is 2.76×104 m3. The maximum magnitude of Richter scale of the seismicity corresponding to the fault reactivation is 3.15. The case study described in this paper provides an integrated workflow for feasibility study of CRI based on 3D geomechanics analysis. A best practice for this type of CRI design is also presented.
Use Of Fiber Materials to Mitigate Lost Circulation During Cementing Operations in Turkmenistan
Authors: Bugrayev Amanmammet , Nafikova Svetlana , Taoutaou Salim , Gurbanov Guvanch , Hanov Maksatmyrat , Rathod Vishal 
Published: June 2021

Abstract
Lost circulation in depleted sands during a primary cementing job is a serious problem in Turkmenistan. The uncertainty in formation pressure across these sands increases the risk of losses during drilling and cementing, which results in remedial operations and nonproductive time. The need to find a fit-for-purpose lost circulation solution becomes even more critical in an environment with narrow pore pressure-to-fracture gradient, where each cement job with losses compromises the downhole well integrity.
An engineered lost circulation solution using innovative materials in the cement slurry was carefully assessed and qualified in the laboratory for each case to optimize the formulation. The lost circulation control treatment combines specialized engineered fibers with sized bridging materials to increase the effectiveness of treatment, formulated and added to the cement slurries based on the slurry solids volume fraction (SVF). Cement slurries with low SVF were treated with higher concentrations of the product and slurries with high SVF used lower concentrations.
More than 50 jobs were performed with cement slurries designed at various densities and SVF up to 58% and using this advanced lost circulation material (LCM) to mitigate losses during cementing. Field experience showed positive results, where the differential pressure up to 2,800 psi was expected during cementing operation. A local database, generated based on the design and development work performed, enabled improved decision-making for selection and LCM application requirements for subsequent jobs and development of a lost circulation strategy. The mitigation plan was put in place against losses in critical sections and depleted sand formations in Turkmenistan. It assisted in meeting the cement coverage requirements on numerous occasions, improving overall the integrity of the wells and thus, was considered to be a success.
This paper provides insight of this advanced LCM, its application in cement slurries, the logic behind the developed loss circulation strategy, and the high success rate of its implementation. Three case histories are presented to demonstrate the strategy and results.