bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating Cement Integrity through Industry's First LWD Full Range Quantitative Cement Bond Index: A Game Changer in Deepwater Wells
Authors: Saumya Sachit , Singh Juli , Vij Jitesh , Sarkar Sujit , Das Bhaswati , Shedde Preetika 
Published: April 2019

Abstract
Cementing forms an essential part of well construction as it supports the casing and provides hydraulic sealing. Wireline (WL) sonic tools have been providing the cement evaluation (CBL/VDL) for more than 50 years. Quantitative cement evaluation is becoming increasingly important in the industry to verify well integrity and zonal isolation. There has been a growing interest in providing cement bond quality quantitatively with LWD sonic tools owing to its plethora of benefits over wireline logging, such as rig time saving, tool conveyance, less tool eccentering effect and timelapse evaluation. However, there is also an LWD specific challenge that has for long hindered the ability to measure quantitative bond index i.e. drill collar contamination which limits the range of cement bond evaluation with the conventional amplitude-based approach. Deriving a characteristic correlation of attenuation measurement against the bond index was one of the key components to overcoming the limitation of amplitude-based. A new hybrid processing approach combining amplitude and attenuation was established for full-range cement bond evaluation. Schlumberger's LWD multipole sonic Cement Evaluation Service delivers the industry's first quantitative bond index answer product on LWD platform. The quantitative bond index becomes even more critical in offshore and deepwater markets.
This paper discusses, in brief, the technology and associated challenges in delivering industry's first quantitative bond index and showcases the result for one of the deepwater well. A subsequent comparison of LWD multipole sonic cement evaluation results with conventional WL CBL-VDL further corroborates the reliability of the result. The performance of the industry's first LWD bond index derived using LWD multipole sonic from around the globe has demonstrated that it can be expected to show abundant success in expanding the LWD utilization globally
Innovative Mini-DST and Production Evaluation Approach at Challenging HPHT Condition for KeShen Tight Gas Reservoir, a Case Study at Tarim Basin
Authors: Shuai Shichen , Zhang Xinlei , Ma Tengfei , Zhao Yuanliang , Guo Qingbin , Chen Jichao , Fan Zhaoya , Bi Bo , Yang Lei 
Published: April 2019

Abstract
KeShen block at Tarim basin is one of the most important gas reserve for PetroChina. The single well gas production at KeShen area can be as high as million cubic meters per day. However, the complex geology settings of KeShen area lead to significant difficulties on the engineering aspects from the drilling, logging, completion to testing. The reservoir is below a salt layer, having a nature of high pressure and high downhole temperature. Often, the reservoir section must be drilled with 6in hole or even smaller hole size. The combination of challenges: ultra-deep (more than 6000 meters), high temperature, high pressure and slim hole cause the testing operation usually lasts for a few months in time and costs a few million dollars, which is extremely expensive for a land well. Mini-DST with formation testers therefore is considered as an alternative option to providing the necessary fluid, pressure and productivity information.
The main target of the reservoir sand is tight, the permeability is ranging from 0.01 mD to 1mD. Mini-DST operation was not feasible in such challenging environment with the conventional formation testers in the market. A recent introduced new equipment, named 3D radial probe fitting for the slim hole allow a feasibility trial for mini-DST in KeShen area. By the design, the new equipment can work in 6in open hole and provide max. 8000psi pressure drawdown capability. A simulation work has done to confirm this high drawdown can enable the gas flow from the formation to accomplish the testing.
A numerical approach, which integrating all the logging data set and the mini-DST result, is conducted to understanding the production potential of the well. A single well numerical model is created using the logging data, the permeability is carefully calibrated with the mini-DST interpretation, the hydraulic fractures can also be added to the model for feasibility study on well stimulation.
In the last 2 years, multiple wells were selected in KeShen area to do the mini-DST with the new 3D radial probe, the results were very promising. The mini-DST done in the trial wells provide high quality PVT gas samples, high quality pressure transit data for permeability interpretation. The numerical production evaluation also matches very well with the DST result later for comparison. The whole mini-DST operation takes only a few days including conditioning the mud, which is a signification saving on the time and cost. All the cases in these wells will be reviewed and discussed.
With this confirmative result of the work, Mini-DST becomes the first option to test a well at KeShen area if the well condition allowed to reach optimal balance between the data obtained and operation cost.
Successful Execution of a Challenging Well Intervention on First of its Kind Unconventional Dual Completion Well in South East Kuwait Field: A Case Study
Authors: Saffar Ali Hussein , Haddad Hassan , Sindhu Sneh , Gupta Pravind Kumar , Al-Munayes Fahad 
Published: April 2019

Abstract
KOC has been producing oil using dual completions from different pressure regime zones from the same well and South East Kuwait field has many such dual completions wells which are currently being converted from natural flow completion to artificial lift completions. In one of such dual completion naturally producing well, first time in world an artificial lift system - Anchor Pump was installed in Short String (SS) through rigless intervention. Thus project well had un conventional dual completion in the field first of its kind i.e. Sucker Rod Pump (SRP) installed in short string and natural producer through Long String(LS). The well produced for some time through both strings and an intervention by workover rig was required due to high water cut and stuck anchor pump in short string. The paper describes the challenges and initiatives and learnings for safe execution of unconventional dual completion well workover.
Due to combination of natural flow and SRP artificial lift completion, the X-mas tree configuration and associated surface equipment of such well was had several constraints and HSE issues for mobilization of rig and dual production zones with varying pressure regimes have challenges of initial well killing due to plugged short string by stuck anchor pump. The risks were identified during planning stage and risk reduction measures were jointly agreed with Field Development. Various options were explored to minimize risks to ALARP level and subsequently addressed in Work Over Program. The surface equipment constraints were eliminated through rigless works and X-tree configuration were modified to suit deployment of a workover rig. Well process safety principles were applied to accomplish initial well killing in both production zones so as to safely pull out existing dual string completion without any well control issues. An initiative to use sucker rod back off tool, first time and safe back off operation was performed successfully from very close to stuck point.
The existing completion strings were pulled out and further well cleanout and workover program was well cleanout Finally, well was completed with new ESP completion string and successfully production tested. The most important factor in success was proactive planning keeping in view of Process Safety for well control issues and effective communication among the concerned parties.
The initiatives adopted in execution of such a challenging well intervention resulted enhancement in safety to rig crew and Rig operational safety standards in addition to contribution towards cost reduction. Lessons learnt has potential of rig time saving specially during workover of large number of heavy oil wells where stuck sucker rod conditions are very common due to sand invasion in tubing during production.
Tap the Potentials and Reduce the Geological Uncertainties of Mature Complex Fluvial Reservoir: Case Study Redevelopment Plan of D-X Oilfield in Bohai Bay
Authors: He Yifan 
Published: April 2019

Abstract
D-X oilfield implemented an infill adjustment from 2013 to 2015, adding 101 development wells, two central processing platforms and two wellhead platforms.
After the adjustment, the oil field greatly improved the engineering processing capacity, but it had also entered a period of rapid decline. In order to mitigate the decline and improve the recovery rate, 65 adjustment wells were implemented in this oilfield after the first adjustment. Based on the new drilling data and production data, earlier inefficient well management was turned a more efficient well management, where the engineering processing space is fully utilized, the decline of oil field is alleviated, and the development effect is greatly improved.
This this paper expounds how to excavate the potential again after the redevelopment project in large fluvial facies oilfield in Bohai bay, taking this oilfield as an example.
A Novel Technique Applied in Early-Time Pressure Transient Analysis for Fractured Wells with Unpropped Segments
Authors: Luo Le , Cheng Shiqing , Dai Li , Wang Yang , Zhang Jiaosheng , Ma Changlin , Yu Haiyang 
Published: April 2019

Abstract
Propping agents inside hydraulic fractures perform significant role in constructing high-speed flow channel to deliver fluids into wellbore. However, proppant transport in fracture is always influenced by many factors, resulting unpropped fracture. Under such situation, this paper proposes a novel pressure-transient analysis method to better interpreted created fracture properties. The application of signal amplification technology is conducted on pressure transient analysis to deal with non-uniqueness problems. Aiming at transient linear flow, trilinear flow model in fractured wells is further modified and upgraded to characterize unpropped segments. Based on the solutions, this study applied signal amplification technology to extract weak-signals to assist early-time pressure transient analysis. The new type curves regarding with pressure response in partially unpropped fracture is then generated to capture the characteristics of this phenomenon. Subsequently, sensitivity analyses make clear the effects of key parameters on pressure response, which shows the superiorities of the new type curves in pressure transient analysis. The approaches proposed by this paper undoubtly will help solve inverse problems of wells exhibiting long-period linear flow in tight reservoirs.
Generating Geologically Realistic 3D Reservoir Facies Models Using Deep Learning of Sedimentary Architecture with Generative Adversarial Networks
Authors: Zhang Tuanfeng , Tilke Peter , Dupont Emilien , Zhu Lingchen , Liang Lin , Bailey William 
Published: April 2019

Abstract
This paper proposes a novel approach for generating 3-dimensional complex geological facies models based on deep generative models. It can reproduce a wide range of conceptual geological models while possessing the flexibility necessary to honor constraints such as well data. Compared with existing geostatistics-based modeling methods, our approach produces realistic subsurface facies architecture in 3D using a state-of-the-art deep learning method called Generative Adversarial Networks (GANs). GANs couple a generator with a discriminator and each uses a deep Convolutional Neural Network (CNN). The networks are trained in an adversarial manner until the generator can create "fake" images that the discriminator cannot distinguish from "real" images. We extend the original GAN approach to 3D geological modeling at the reservoir scale. The GANs are trained using a library of 3D facies models. Once the GANs have been trained, they can generate a variety of geologically realistic facies models constrained by well data interpretations. This geomodelling approach using GANs has been tested on models of both complex fluvial depositional systems and carbonate reservoirs that exhibit progradational and aggradational trends. The results demonstrate that this deep learning-driven modeling approach can capture more realistic facies architectures and associations than existing geostatistical modeling methods, which often fail to reproduce heterogeneous nonstationary sedimentary facies with apparent depositional trend.
Experimental Investigation of the Impact of Modified Nano Clay on the Rheology of Oil Well Cement Slurry
Authors: Murtaza Mobeen , Mahmoud Mohamed , Elkatatny Salaheldin , Majed Abdulaziz Al , Chen Weiqing , Jamaluddin Abul 
Published: April 2019

AbstractIn cementing operations of deep oil and gas wells, long term integrity of the well is highly dependent on the cement sheath. Obtaining success rate in cementing operations has been subjected to a myriad of challenges, as drilling into deeper, high pressure/high temperature horizons is done. To gain long term integrity of cement sheath, a successful placement of cement slurry plays a pivotal role. So, the design of suitable rheological properties helps characterize the cement pumpability, mixability, and displacement rates for adequate removal of mud. So, the design of cement slurry for HPHT and deviated wells has become a complex task. Recently employing nano-materials in improved oil recovery, designing of drilling fluids as well as hydrocarbon well cementing has been the focus of many studies. The intrinsic characteristics of being smaller in size, while at the same time providing a larger surface area, nanomaterials can prove to be a game-changer for the challenges faced in HPHT cementing. This paper reproduces the outcomes of an investigational study conducted to determine the effect of nanoclay as an additive on rheological properties of Type-G cement slurry under various temperature conditions. Nano-clay with Class G cement in two different concentrations 1% and 2% by weight of cement, mixed and tested under different temperature conditions (37°C, 50°C, 60°C & 80 °C). Additionally, nano-clay based cement mixtures were prepared by substituting cement with 1%, 2% and 3% of nano-clay by weight of cement(BWOC), and admixed with silica flour, along with various chemical admixtures. American Petroleum Institute (API) standard-10B was followed to condition the slurry at predetermined temperature, while the slurry was under atmospheric pressure. This conditioning was followed by the measurement of rheological properties. Results of this investigation demonstrate that incorporation of nano-clay advances the rheology of prepared cement slurry that could aid in mud-displacement and anti-settling as per the requirements.
Artificial Lift Methods Optimising and Selecting Based on Big Data Analysis Technology
Authors: Shi Junfeng , Chen Shiwen , Zhang Xishun , Zhao Ruidong , Liu Zhaoyu , Liu Meng , Zhang Na , Sun Dakui 
Published: April 2019

Abstract
The best artificial lifting method for a well is to lifting more with less during the whole life cycle, however, it is difficult to select the best method because there are many factors affecting the choice of artificial lifting methods and most factors cannot be described with mathematical models. At present, the selection mainly depends on experts’ experience, which results in many incorrect decisions and lead to huge economic loss. In China, there are a large number of artificial lifting wells, and the large amount of data generated by the wells is of great value, which can be used to select the best artificial lifting method for different type of oil wells. This paper selects 11 parameters, including well fluid characteristics, fluid production capacity, well trajectory, pump depth, pump efficiency, pump inspection period, and maintenance cost per year as influence factors. About 40,000 artificial lifting wells of CNPC were selected as the big data analysis sample initially. As not all the wells are good samples, an effect evaluation function is established by taking pump efficiency, power consumption with lifting per ton liquid 100m, annual operating maintenance cost into account, then the samples are selected further according to the value of effect evaluation function, which ensured all the samples participated in machine learning are good samples. A deep recurrent neural network was established which can select the best artificial lifting method through deep learning. Experimental results showed that the neural network model had fast convergence and high prediction accuracy. With the application of this model, artificial lifting method selecting and effect analysis have been conducted for more than 5,000 oil wells of CNPC with different reservoir characteristics, different wellbore structures and different fluid characteristics. The coincidence rate between calculation results of this model and actual production situation is 90.56%. Big data analysis provides a reliable, practical and intelligent method for optimizing and selecting artificial lift.
Drilling Dynamics Measurements on Positive Displacement Motors PDM Enhance Performances and Reliability
Authors: Li Fei , Neelgund Rohan V. , Smith David L. , Blackman Wesley 
Published: April 2019

Abstract
Positive displacement motors (PDMs) have been extensively utilized in the North America unconventional market. PDMs are frequently run with aggressive parameters in challenging drilling environments to increase drilling performance. Because PDMs are typically rental equipment, there is often not much information givento the equipment owners when tools are returned after use. This situation limits the opportunities for failure investigation, preventive maintenance, and tool design optimization. Furthermore, measurement-while-drilling (MWD) tools in PDM bottom hole assemblies (BHAs)only measure dynamics of the drill collars, considerably above the motor, often without sufficient resolution to understand adverse drilling dynamics and to design remedial actions for the operations.
A dynamics measurement data recorder was developed and introduced for this type of operation. The data recorder is a small, low-cost, and battery-powered device. It is installed in the rotor catch of a conventional PDM in such a way that no additional component is added to the BHA length. The recorder is fitted with a triaxial vibration accelerometer, a triaxial shock accelerometer, a gyroscope and a temperature sensor. The recorder can log data over a full PDM operation cycle, including shipment, rig-side handling, and downhole operation.
The data recorder has been deployed in North American land operations since 2016. One case study is presented, and the data analysis showed that PDM operation cycles were captured from the installation of the recorder in maintenance bases to the return of the tools. Torsional vibrations and stick-slip generated by mudmotors during sliding phases were effectively captured. In several cases, bit dull grade conditions were correlated with recorded drilling dynamics data as part of failure analyses to understand the root cause of the problem.
A Dynamic Characterization Approach for a Complex Naturally Fractured Reservoir
Authors: Alcantara Ricardo , Santiago Luis Humberto , Fuentes Gorgonio , Garcia Hugo , Romero Pablo , López Pedro , Angulo Blanca , Martinez Maria Isabel 
Published: April 2019

Abstract
The Naturally Fractured Reservoirs (NFR) constitute a challenge for the oil industry due to its importance in hydrocarbon production and the technical complexity they represent, because well’s productivity in carbonated formations is influenced by fracture systems that govern the fluids motion within reservoirs.
This approach is oriented to the analysis of a very complex NFR, where we show the results obtained through a dynamic characterization methodology focused on new opportunities in a High Pressure-High Temperature (HP-HT) coastal mature oilfield with high water cut production. The proposed methodology is based on a full analysis starting from the pressure-production historical data, fluids properties, dual-porosity material balance, a detailed static model update (petrophysics, core analysis, petrography, fracture analysis, sedimentology-diagenesis and structural geology), flow units discretization, Water-Oil Contact (WOC) advance monitoring in each block, Pressure Transient Analysis (PTA) (determination of preferential flow direction and interference), and Rate Transient Analysis (RTA).
This methodology allowed to determine the real Original Oil in Place (OOIP) and the proper recovery factor according to the type of NFR and its characteristics, to detect different WOC’s for each block that were hydraulically connected to each other but with a different dynamic behavior among them, the detection of heterogeneities, facies changes and faults that originally were not mapped, sweet spots location, better distribution of the petrophysical properties, fracture analysis, static model reinterpretation based on the dynamic behavior, reservoir connectivity analysis (among blocks) and the generation of improved production forecasts based on an exploitation strategy especially designed for the current conditions and needs of the field; all of this contributed to have a better understanding of the reservoir and a good numerical simulation model.
Research of Formation Protection Technology in Complex Fault Block Oilfield
Authors: Fan Songlin , Wang Xiaofang , Dong Jun , You Qiuyan , Yang Xiaochun , Zhao Junfeng 
Published: April 2019

Abstract
Dagang Oilfield is a part of oil-gas reservoir with various reservoir types, broken fault block, high heterogeneity and complex geological situations. For example, in low pressure and high permeability reservoirs, permeability is higher than 2000 mD and pressure coefficient is less than 0.5. The salinity of formation water in low permeability reservoir is as high as 30000 mg/L, and the pour point of crude oil is as high as 40 °C. The statistics show that the average recovery time of the well yield after remedial work is over 7 days, and the average recovery rate of the well yield is less than 87% in Dagang Oilfield, which have an influence on the stable production and the benefit development of the oilfield. The problem above has not been effectively resolved for a long time because of the factors of technology and cost. In this paper, a series of low cost formation protection technology were developed. First, the low-cost nitrogen microbubble temporary blocking technology, which can block 2 mm aperture, was developed by improving preparation technology of nitrogen microbubble working fluid and adding degradable temporary blocking material. Second, the formation protection for complex low-permeability reservoirs was developed by enhancing the temperature of workover fluid and adding the high efficiency surfactants. The results show that the temperature of workover fluid increases by 20-50 °C. Finally, the low-cost workover operation technology with formation protection was developed. The cost can be reduced more than 50% while protecting the formation. So far, the all technologies were successfully applied in 2135 wells. After the application of technology, the average recovery time of the well yield is 3.5 days, the average recovery rate of the well yield is 96%, and the total production loss is 15.7 ° 104t. The problem of the formation pollution during the workover has been effectively resolved, which provides technical support for the production stability of complex fault block oilfield.