bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo Optimization for Site Selection of Process Facilities in Oilfields Considering Environment
Authors: Wang Bohong , Liao Qi , Zheng Jianqin , Yuan Meng , Zhang Haoran , Liang Yongtu
Published: April 2019

The site selection of the facilities in oilfields is one of the important issues for surface engineers. In the progressive development of oilfields, new wells are explored and developed, and new process facilities (PFs) should be constructed to gather and process the fluid from these new wells. The emission of the PFs will affect the surrounding environment, including water sources, forests, and human settlements. Thus, the environment should be considered as one of the key aspects in the design process of facilities. Different locations of facilities in the oilfields will affect both the construction cost and environmental cost. Thus, a balance has to be found. In addition, the uncertainty of production rate of well fluid poses a great challenge to this problem. To solve the above problem, this paper provides a systematic methodology.

The objective function consists two parts: construction costs and environmental cost. The solving algorithm has involved three layers of looping programming to calculate the value of objective function. First the weather conditions are generated by the Monte Carlo method, then the second loop is for the study areas, and the third loop is for the new facilities locations. After all the loops of iterations are completed, the objective functions are calculated, and the influence of the environment can be evaluated. Finally, the best solution can be obtained.

The effectiveness of the proposed method is demonstrated through a design problem in an oilfield. The candidate locations for PFs are previously determined, and the optimal construction plan is solved by our method. The quantitative influence on the environment to these candidate locations can be evaluated. After determining the coefficient of the construction cost and the environmental cost, the best locations for the process facilities with the lowest total cost can be determined.

A multi-objective model for the site selection of process facilities in oilfields is proposed, which has not been done by existing literatures. The construction cost and surrounding environment are both considered in the model. This work has the potential to serve as a decision-support tool for surface engineers in oilfields.
Study on the Phase Equilibrium of Gas Hydrate Based on Main-Branch Pipe Confluence Model
Authors: Deng Song , Liu Yali , Wei Xia , Tao Lei , He Yanfeng
Published: April 2019

Phase change, a major factor that restricts the development of gas hydrate, is likely to cause blockage in well completion section (sieve section – wellbore lifting section), thus resulting in the engineering losses. In view of the defects in the previous studies on the confluence mechanism of completion section of gas hydrate pressure drop method mining under openhole completion technology, the flow of gas hydrate in the well completion section was simplified as the Main-Branch pipe confluence model in this paper. Firstly, a physical model was established. On the basis of the energy conservation law and the Peng-Robinson equation, the temperature and pressure coupling model was also derived. Then, the Fluent software was used to simulate the temperature gradient and pressure gradient changes in the Main-Branch model. The gas hydrate phase diagram and P-T environment under different velocity were obtained. Finally, the contrast analysis between theoretical model and numerical simulation was carried out and the established model was verified. Through the study of this paper, it is possible to prevent blockage of the well completion section by means of depressurization, which can provide theoretical guidance for the control of pressure drop when gas hydrate is extracted by depressurization. It is important for the exploitation and continuous production of gas hydrate in the later stage.
Development of a New Parallel Polymer Flooding Simulator for Conventional and Naturally Fractured Reservoirs
Authors: Liu Hui , Chen Zhangxin , Shen Lihua , Zhong He , Liu Huaqing , Yang Bo , Ji Dongqi , Zhu Zhouyuan , Zhan Jie
Published: April 2019

This paper deals with the development of our parallel reservoir simulator that is designed for giant reservoir models. It considers oil, water and polymer, and a reservoir can be a conventional reservoir without fractures or a naturally fractured reservoir. For polymer flooding, the simulator can model polymer retention, adsorption, an aqueous phase permeability reduction and viscosity increase, and an inaccessible pore volume. Here fractures are modeled by the dual porosity and dual permeability method. The finite difference (volume) method is applied to discretize the model, upstream techniques are employed to deal with rock-fluid properties, and the fully implicit method in time is applied. The linear systems from the Newton method are ill-conditioned and a scalable CPR-type preconditioner is employed to accelerate the solution of these linear systems. The computed results are compared with those from commercial simulators, and they match very well. The scalability of the simulator is good.
Novel Non-Damaging Hybrid System for Sand Consolidation Application
Authors: George C. Shoy , Nguyen D. Philip , Patil Prajakta
Published: April 2019

Sand consolidation technology has evolved in recent years to accommodate more rigorous requirements with regards to health and safety, operations, downhole conditions, and high production flow rates. Because of stricter environmental requirements, most operators prefer to apply aqueous-based consolidation treatment fluids instead of solvent-based fluids. However, clay-laden formations can be sensitive to water, and thus the use of aqueous-based treatment fluids is problematic in these formations, especially in those with high clay contents.

This paper presents an aqueous, silane-based resin system for stabilizing and strengthening unconsolidated formation sand surrounding a wellbore. The chemistry of this silane-based treatment fluid was determined to effectively treat large surface areas of formations containing high clay concentrations, while providing high bonding strength between sand grains without plugging their intergrain pore spaces to retain the high permeability of the treated formation. Rather than depending on complete consolidation of formation materials surrounding the wellbore for successful sand control, the new resin enables agglomeration of formation particulates to form aggregates or clusters, thus helping to prevent them from passing through slotted liners or sand screens.

Rock mechanics evaluation of clay-laden sands treated with this new resin system shows that they possess elastic properties and survive the effects of stress cyclic loading. Scanning electron micrographs (SEMs) of the consolidated core material clearly reveal the formation of a porous network of fines and sand, causing little damage to the porosity and permeability of the treated formation. This new resin system provides an alternative to conventional sand control completion in lower quality reservoirs, as well as an effective through-tubing completion alternative. The treatment helps ensure the effectiveness and longevity of standalone screens, thus providing operators with an economical means for well completion.
A Holistic Approach to Life Extension of Fixed Offshore Platforms in Malaysian Waters
Authors: Ng Sok Mooi , Khan Riaz , Isnadi Biramarta , Lee Luong Ann , Saminal Siti Nurshamshinazzatulbalqis
Published: April 2019

The objective of this paper is to share the holistic approach to managing aging fleet for offshore fixed steel structures. PETRONAS is currently operating a fleet of more than 200 fixed offshore structures in Malaysian water. More than half of it has exceeded the original design life. With enhanced oil recovery and other developing technologies, offshore platforms often than not are required to continue operating beyond its original design life.

A holistic approach for life extension of fixed offshore structures are being developed to ensure safe operations of the facilities. PETRONAS has started SIM journey since 2007. The approach of Data, Evaluation, Strategy and Programme in line with API RP 2SIM set the basis for managing the integrity of the offshore fleet. An integrated solution was developed to manage both topsides and substructures. The Structural Integrity Compliance System (SICS) which houses the integrity management of topsides deteriorations to prioritize resources through risk based anomalies management. Risk based underwater inspection also formed part of the solutions, addressing mainly extreme storm in the region. Other Major Accidental Hazards (MAHs) risk ranking included in SICS are vessel collision and seismic. Management of facilities with minimal redundancy such as guyed wire monopod is addressed through time based inspection. A regional hazard curve is also developed to ensure the facilities are meeting the acceptance criteria set forth by the industry.

Besides aging, other integrity triggers including shallow gas and subsidence required a different scheme in managing the integrity of the facilities, primarily addressed through a comprehensive monitoring programme.

There is no one size fit all recipe in managing the aged platforms for life extension. The data plays a crucial role in ensuring the right methodology is deployed in support of digitalization and data driven decision making. Implementation of the system is proven to be reliable in ensuring the offshore fixed structures are intact to support safe and continuous operations to the operator in a cost optimum manner. The data analytics help to enhance the predictive model to optimize the inspection and maintenance programme.

Strong ownership and commitment of the structural integrity engineers in ensuring the data integrity maintain the challenge in sustainability of the system and provide reliable source for data driven decision making to the operator.

Category: Operational Excellence (136 - Managing Aging Facilities)
Using Deep Kalman Filter to Predict Drilling Time Series
Authors: Yu Yingwei , Liu Qiuhua , Chambon Sylvain , Hamzah Mohammad
Published: April 2019

Drilling automation design can benefit from simulated data. A drilling timeseries simulator can enrich the dataset for testing, and enable the inference of the drilling states in real time; however, conventional simulators based on simplified physical models usually lack the vivid patterns seen in real datasets. In this paper, we present a solution that uses a deep neural network-based Kalman filter. This system learns from real data, characterizes the different drilling responses, and conditions the data.

The dynamics of a rig drilling system can be modeled as G(P, E, U) → Z, where P is the plant of the rig mechanical system, E the environment (i.e., the earth, formations, etc.), U the rig controls (e.g., the top drive RPM, the flow rate, etc.), and Z the measurement (e.g., the hookload). The dynamics can be described with a non-linear Kalman filter. The Kalman filter contains components of internal states, inputs, and measurements, and transfer functions for the internal states, inputs, and measurements. We model these transfer functions with deep neural networks, and solve these transfer functions by training with real data. The implemented deep neural network model contains components of convolutional neural network layers, long short-term memory layers, and deconvolutional layers.

We trained the neural network with a real drilling datasets. Two experiments are presented. In the first one, the inputs are time-windowed multiple channels of RPM, block position, slip status, flow rate, and weight on bit, and the outputs are the response channels of torque, ROP, hookload, standpipe pressure, etc. The training accuracy achieved 99.5% after 50 epochs. In the second experiment, the network is trained to predict 16 rig states.

In summary, the introduced deep neural network is a generic model for generating simulated time series and classification tasks.
The Application of Cyclone Desorption Technology for OBM Drill Cuttings Disposal
Authors: Wu Jiwei , Pan Jiake , Wang Hualin , Wang Lixiang , Lan Xiaoping , Yang Lijie , Liu Wenjin
Published: April 2019

With the flourishing shale gas exploitation produces more oil based mud (OBM) drill cuttings, the hard-to-treat hazardous waste burden the local environment heavily. However, the problems of high energy consumption, high treating cost and high secondary contamination risk still remain unsolved for mainstream technologies such as thermal distillation, incineration and chemical extraction. Therefore, a new method and device based on cyclone desorption of high speed self-rotation to dispose of OBM drill cuttings are put forward to overcome the challenge.

The working process includes: viscosity reduction in heated gas; cyclone deoiling; condensation and recycling of exhaust; separation of oil and water in coalescer. It is found that the self-rotation speed of solid particles in a 3-dimensional rotating turbulent flow field of cyclone is as high as 2,000 to 6,000 rad/s which coexists with revolution speed of 20 to 300 rpm. The remarkable pulsing centrifuge forces in the self-rotation and revolution coupling motion can enhance the desorption process of the oil so as to accomplish the separation and enrichment of oil and solid phase, and deep removal of organics from OBM drill cuttings.

It turned out that the deoiling efficiency of OBM drill cuttings, a sample from Chongqing shale gas field, increased as the processing time longer and, to be exact, after 2.1 seconds the oil content fell from 17.9% to 0.16% which is about a half of the maximum allowable content of petroleum in pollutants, 0.3%, in GB 4284-84 "Control Standards for Pollutants in Agricultural Sludge".

In general, the innovation of cyclone desorption of high speed self-rotation is the pulsing centrifuge force of self-rotation and revolution coupling motion, so it's free of chemical addition and high heating temperature. Therefore, the application of cyclone desorption of high speed self-rotation for OBM drill cuttings disposal is expected to lower treatment cost, enhance processing effect, and finally improve the environment of shale gas exploitation area and contribute to energy development.
General Guidelines for Batch Treatments of Polylactic Acid for Diversion in Multistage Matrix Acidizing Treatments
Authors: Shirley Robert , Hill A. Dan
Published: April 2019

In the last decade, there have been several publications describing the use of Polylactic Acid (PLA) as a diverting agent in multistage matrix acidizing treatments. The solid polyester is particularly useful as a diverting agent because it hydrolyzes in the presence of heat and water leaving no residue in the formation, negating the need for any clean-up fluids. Most of the publications thus far focus on characterizing the physical and chemical attributes of the diverter and demonstrating its effectiveness in field trials. This paper develops some general guidelines for the application of PLA diversion in multistage matrix acidizing treatments by conducting sensitivity analysis on the design parameters of three field cases.

To carry out these sensitivity analyses, an empirically derived model that describes how PLA creates a skin factor during multistage matrix acidizing treatments is incorporated in a near wellbore simulator. This simulator also tracks the fluid interfaces, models the transient reservoir and wellbore flow, and calculates the wormhole propagation rate and a number of completion skin factors. The design parameters that will be investigated include whether PLA should be sized to enter the wormhole or to bridge at the sand face, diverter concentration, specific cake resistance, the number of diverter stages, and the total volume of acid pumped. The efficiency of the diversion treatments will be compared based on the overall final skin factor and uniformity of the skin profile along the well.

This paper reveals that PLA is significantly more effective in creating a uniform skin profile if it is designed to bridge the wormhole openings rather than to enter them. It is also shown that increasing the diverter concentration or using a diverter with a higher specific cake resistance can create a more uniform skin profile but there is an inverse relationship with the overall skin factor. It is shown that using the same volume of the diverter in a few diverter stages is better than pumping all of the diverter at once, but that there is a limit where using a larger number of stages does not add any benefit. The study highlights the need to fully stimulate the high permeability zones before pumping the PLA, and finally, it suggests that the total volume of acid used should be higher when PLA diversion is used to offset the adverse effects on the overall skin factor.
Comprehensive Seismic Data Conditioning of the Bioclastic Limestone in the Middle East
Authors: Lin Tengfei , Wang Xueling , Dong Junchang
Published: April 2019

The bioclastic limestone reservoirs of Cretaceous period occupy an important position in the petroleum industry of Middle East. It is the carbonate heterogeneity that is challenging the accuracy of the reservoir prediction, which brings forward higher requirements for the seismic data quality. Besides, some seismic data are processed more than 10 years ago, the signal to noise ratio (SNR) is relative low due to the random noise and coherent noise like acquisition footprint anomalies. The acquisition footprint artifacts caused by acquisition and processing seriously suppress the true stratigraphic features, which can result in pitfalls in seismic interpretation, seismic attribute analysis as well as seismic inversion. While the pre-stack seismic data is usually unavailable, which means that the noise can hardly be subtracted by conventional pre-stack seismic processing workflows, such as statics, high-resolution velocity analysis and ground roll attenuation. Consequently, a comprehensive post-stack seismic data conditioning workflow is necessary to solve the above problems.

In order to improve the post-stack seismic data quality, a comprehensive data conditioning workflow are applied for noise suppression. Firstly, structural-oriented filtering is utilized to attenuate random noise and partial acquisition footprint artifacts. Then 2D waveform transform of seismic amplitude and filtered seismic attribute in x-y domain are calculated, to separate acquisition footprint anomalies (large wave number in kx-ky domain) from true structural signal (small wave number in kx-ky domain) by interactive analysis. The application of Laplace-Gaussian (LoG) filter deserves an obvious improvement in acquisition footprint suppression workflow. The comprehensive noise attenuation workflow in this paper can effectively remove both periodic and non-periodic noise to obtain higher signal to noise ratio (SNR) for post-stack seismic volume. In this way, the stratigraphic features (tidal-channel, reef-beach complex) can be more clearly depicted and some artifacts caused by noise will disappear in seismic attribute calculation, seismic inversion and reservoir prediction.
ROP Enhancement of Hydro-Efflux Hammer in Hard and Abrasive Formations
Authors: Li Bodong , Zhan Guodong David , Suo Zhongwei , Sun Mingguang
Published: April 2019

This paper introduces the hydro-efflux hammer - a rotary percussion drilling tool that is developed to improve ROPs in hard and abrasive formations. Hydro-efflux hammer is a hydro-mechanical tool which utilizes drilling fluid to power its continuous percussion motion. The tool’s rock-breaking capability is achieved by the high unit load and unique breaking methods. The periodic impact generated by the tool excites strong pulsating stress waves, which strengthens the concentrated stress in internal rocks, and speeds up the rock breaking process. For the design of the tool, improved system integrity is achieve by implementing optimized actuating mechanism, sealing components, and anticorrosion materials. The optimization also involves fine tuning the tool including its percussion stroke and impact energy based on the formation characteristics. Recent field test results in challenging formations are presented and analyzed. In this work, based on the testing result, a number of approaches to extend the life time of the tool for higher performances are also proposed.
Adverse Effect of Oversizing Upstream Gas Oil Separation Plants on Energy Consumption
Authors: Soliman Mohamed Ahmed
Published: April 2019

The objective of this paper is to highlight the adverse effect of oversizing upstream surface facilities on energy consumption and different techniques to improve the energy performance of these oversized facilities. Oversizing may provide short-term gain as insurance policy for the design team but long-term loss for the operating organization.

In this paper, the mindset and consequences of oversizing surface facilities rotating equipment, piping, and heat exchangers on energy consumption are depicted with real-life case studies. In addition, a systematic approach to eliminate oversizing in Greenfield projects and to mitigating their adverse effects on existing facilities are addressed in detail. The paper focuses on a comprehensive case study of oversizing crude charge pumps in one of the gas oil separation plants GOSPs (Plant-A).

Extensive process simulation using Hysys and benchmarked by the actual plant energy consumption data indicated that oversizing of pumps, heat exchangers, and compressors increase energy consumption dramatically and lower the overall plant performance. It was observed that one of the several reasons for oversizing plant equipment is attributed to the lack of clear guidelines from the proponent governing the maximum design margins allowed. Adequately sized plant equipment will improve plant reliability, minimize energy consumption and plant maintenance, and improve plant safety.
Application of Fuzzy Control Theory in the Study of the Macroscopic Remaining Oil Distribution for a Mature Sandstone Reservoir in the Tarim Oilfield, China
Authors: Sun Jian , Li Chenyang , Zhang Zekai , Ren Long , Li Qi , Chen Mingqiang , Zhang Bo , Tang Kang
Published: April 2019

Research on macroscopic remaining oil distribution (MROD) has become a worldwide issue and not yet been satisfactorily solved in oil industry. At present, the commonly used methods for determining MROD are heavy workload, long time consuming and greatly influenced by human factors. In the research of MROD, geological factors are uncontrollable and development factors are controllable. Therefore, under certain development conditions, geological factors determine the MROD. This paper mainly studies MROD in geological factors.

The new approach is based on development geological principles. It uses fuzzy control theory to predict MROD. Firstly, according to structural location from high to low and clay content from much to less, the structural location parameters and sedimentary microfacies parameters are fuzzified into 5 grades respectively. Secondly, according to the hydrocarbon potential from good to poor, the oil and gas universe is fuzzified into 5 grades. Finally, fuzzy control rules were established. It can be calculated by characteristic expansion method. Complete governing equations are provided and the method is described in detail to permit readers to replicate all results.

The method of using fuzzy control theory to predict MROD has been successfully applied in Tarim oilfield. According to the range of tectonic height and clay content, the membership degrees of structural location parameters and sedimentary microfacies parameters are assigned respectively. LN2-G well in research region is chosen as an example for study. The characteristic coefficients corresponding to LN2-G well under different structure and sedimentary conditions are respectively obtained. Through the fuzzy control statement, and combining the principle of maximum membership degree, the oil level in the target formation of well LN2-G can be calculated, which value is 5, corresponding to the oil layer. Then we use the existing exploration wells in research region, and use the above method to calculate them respectively. Based on the calculated results, we draw the remaining oil distribution level range prediction plan. Finally, we selected 3 wells to verify the accuracy of the prediction. It shows that the reservoirs drilled by LN2-X, LN2-Y and LN2-Z wells are water layer, water layer and poor oil layer, respectively. The actual drilling results of these 3 wells are water layer, water layer and oil-bearing water layer, which are completely consistent with the prediction results.

This research can accurately forecast the MROD based on the analysis of the essential factors (geological factors) affecting the MROD. The method is convenient and economical, which provides a reliable basis for the remaining oil development.
A Reservoir and Geomechanical Coupling Simulation Method: Case Studies in Shale Gas and CBM Reservoir
Authors: Tang Xuanhe , Zhu Haiyan , Liu Qingyou , Song Yujia
Published: April 2019

To investigate the time-lapse, three-dimensional (so-called four dimensional/4D) stress during production/injection, a 4D multi-physical modeling method is proposed. A finite difference method (FDM) reservoir simulator is used to couple thermal-hydrological-chemical (THC) processes, while a finite element method (FEM) geomechanical simulator takes on the role of a thermal-hydrological-mechanical (THM) coupling calculator. Heterogeneity and anisotropy of the reservoir flow and geomechanical properties as well as the permeability stress-sensitivity can be considered in modelling based on field and experimental data. In order to couple the flow model with the geomechanical model, an improved interface (coupling) Python code is provided to communicate data between the finite difference (FD) and finite element (FE) grids. Ultimately, this method is applied to analyze the stress and poro-elastic parameters evolution of hydraulic fractured Sichuan Basin shale gas reservoir and Qinshui Basin coalbed methane (CBM) reservoir in production.
An Equivalent Media Theory for Reservoir Characterization
Authors: Prajapati Srichand , Ghosh Deva
Published: April 2019

The existence of elastic anisotropy in the reservoir is obtained through the equivalent media theory. An isotropic elastic theory fairly explains the reservoir modeling or characterization but its not well explain anisotropic characteristic fairly for reservoir characterization which is extremely challenging without considering a self-consistent theory of effective equivalent media theory. In this research, equivalent media theory has been explained and implemented on a producing well-log data with consistent Vp, Vs, density and other parameters. Instead of using Voigt averaging, equivalent media theory used to estimate the effective stiffness parameters and compare with Thomsen's parameters and finally used effective anisotropy parameters and compare with gamma log. Result shows the effectiveness of equivalent media theory for future application for developing reservoir modeling and characterization.
Recent Development and Remaining Challenges of Iron Sulfide Scale Mitigation in Sour Gas Wells
Authors: Chen Tao , Wang Qiwei , Chang Frank , Aljeaban Norah
Published: April 2019

Iron sulfide scale deposition can be a significant flow assurance issue in the sour gas production systems. It can deposit along the water flowing path from near wellbore reservoir area to surface equipment, which results in formation damage, causes tubing blockage, interferes with well intervention, and reduces hydrocarbon production.

The main objectives of this paper are to review on the new advancements and remaining challenges of iron sulfide scale management in sour gas wells, covering the mechanisms of iron sulfide formation; the mechanical and chemical removal techniques; and the prevention strategies.

This paper gives a special emphasis to the different mechanisms of iron sulfide formation during well completion and production stages, especially the sources of ferrous iron for scale deposition. It is essential to understand the root-cause in order to identify and develop suitable technologies to manage the scale problem. The paper also summarizes the latest developments in mechanical methods and chemical dissolvers for the removal of iron sulfide deposited on downhole tubing. The capabilities of the current chemical dissolvers is discussed and the criteria of effective dissolvers are provided to serve as a guide for future development. Then the paper provides an overview of recent developments on iron sulfide prevention technologies and treatment strategies. It differentiates the treatment approaches for corrosion byproduct and scale precipitation and scale inhibitor deployment through continuous injection and squeeze treatment. Finally, the paper outlines the technical gaps and areas for further research and development efforts.

This paper provides the latest review on irons sulfide formation and mitigation with an attempt to integrate viable solutions and expose workable practices.
Higher Precision Automated Managed Pressure Drilling Control Achieved Through the Addition of a Thermal Model
Authors: Gu Qifan , Fallah AmirHossein , Ambrus Adrian , Chen Dongmei , Ashok Pradeepkumar , van Oort Eric
Published: April 2019

For a robust and efficient automated Managed Pressure Drilling (MPD) operation, the choke controller requires an accurate hydraulics model that can be run at minimum computational expense. Integration of a suitable thermal model would improve the accuracy of the hydraulics model used by the choke controller. The use of existing thermal models, however, comes with additional computational costs that are a hurdle when aiming to achieve real-time control at sufficiently fast time-scales.

In this paper, a quasi-steady thermal model is integrated with an automated MPD control approach that uses a reduced Drift-Flux Model (RDFM) to describe the hydraulics of multiphase flow in real-time. This integrated modeling approach provides the dynamic temperature profile along a well without increasing the computational expense. The energy equation is solved using the finite-difference method (FDM) in an explicit scheme, with all the temperature-dependent parameters updated in accordance with the calculated temperature profile in each computation step. The RDFM is also reformulated to account for the heat transfer between the gas and the surroundings. This modified model is then incorporated into an automated observer algorithm to estimate parameters, e.g. volume of gas expansion (dependent on temperature), which are used by the controller for choke opening manipulation.

Validations are first conducted in a simulation environment for the scenario with a dynamic temperature profile along the well. The results indicate that the proposed modeling approach offers significant improvement compared to approaches which do not consider thermodynamics. A good agreement of the temperature results is observed between the proposed approach and existing models as well as commercial software. Case studies are also conducted for two scenarios to demonstrate the utility of the proposed integrated thermal and hydraulics model. Simulation results indicate that the proposed modeling approach can generate more accurate estimations of unmeasurable variables, which leads to a better performance of the choke manipulation. It should be noted that when employing the modified RDFM with a finite difference scheme, the computational cost is minimized. On a standard laptop computer, the computational time to simulate an entire well is of the order of 70ms for 1s sensor data sampling. Therefore, the proposed thermal and hydraulics model provides an enabling tool for a faster and more precise control of MPD systems.
Integrated Formation Evaluation Using Novel Neutron Correction in the Presence of Trace Elements
Authors: Zhang Hao , Alarcon Nora , Mendez Freddy
Published: April 2019

The estimation of formation porosity in particular and formation volumetrics in general are key to any reservoir evaluation as they establish the hydrocarbon storage capacity. Compensated neutron porosity is one of the most common measurements incorporated in any log-based volumetric analysis. However, this type of measurement is strongly affected by the presence of trace elements, especially in clay rich formations. Trace elements, such as boron and gadolinium, have very high neutron capture cross-sections and absorb large amounts of thermal neutrons in the formation. Whenever these elements are present in concentrations exceeding just a few parts per million they have a significant effect on overall thermal neutron capture, yielding high apparent neutron porosity. When the measurement is included in an integrated log analysis system, this results in inaccurate formation porosity and matrix volumes. A reliable neutron porosity correction method is therefore needed to improve petrophysical evaluation in in such logging environments.

In this work, an integrated model is proposed to correct the compensated neutron response using pulsed neutron spectroscopy measurements and other conventional log data. A joined inversion method is implemented which obtains an improved neutron response by removing the undesirable contributions by the trace elements which are not a part of the formation petrophysical model.

The proposed model is validated, by applying it to several data sets from different shale plays in North America and Latin America, and comparing the results against core analysis data. Due to presence of rich trace elements in the formation, without the correction model, the original processing results indicate up to 50% higher formation porosity when compared with core measurements. After applying the proposed correction, the porosity comparison is dramatically improved, matching the reference core porosity.

The proposed model offers an effective, integrated analysis method, in challenging unconventional clay-rich shale environments, for correct estimation of formation porosity and volumes of mineral constituents.
Stratigraphic Forward Simulation of the Miocene Fan Delta in the South of Albert Basin, Uganda
Authors: Xu Wei , Zhang Yingchun , Fang Lei , Jing Zhiyi , Zou Jingyun , Liu Jun
Published: April 2019

The Albert Basin of Uganda is located at the northern end of the western branch of the East African Rift System. It is a graben rich in oil and gas with a shallow research degree. In the south of the basin, a fan delta system controlled by the boundary fault is developed in the Miocene formation. Due to the few wells and poor quality of seismic data in this area, it is difficult to predict the spatial distribution of sedimentary reservoir sands. In this paper, sedimentary forward modeling coupled with 3D geological modeling is used to provide new ideas for reservoir prediction.

Sedimentary facies analysis is based on core description, well logs, paleontology, heavy mineral content and grain size data. Quantitative analysis of accommodation space, source supply, and sediment transport parameters can help explain the main factors that controlled the sedimentation. Milankovitch cycle method was used to establish the time scale of the basin. The simulation results were combined with 3D geological modeling to quantify the characteristics of the sand body distributions.

Sedimentary facies analysis shows that the Miocene formation in the south of Albert Basin deposited in a shallow lacustrine environment. A proximal fan delta deposition with subaqueous distributary channels was controlled by the east boundary faults. Firstly, the accommodation space was estimated according to the thickness of the stratum and the change of the ancient water depth. The source supply was estimated by the area of the project and formation thickness, and the transportation parameters were estimated according to the nonlinear transportation model based on the traction flow with a little gravity flow. Secondly, an astronomical stratigraphic framework of the Miocene strata in the south of Albert basin was established through the Milankovitch cycle stratigraphy, and it was used to restrain the process of stratigraphic forward modeling and to reproduce the sedimentary evolution process in the geological historical period. Thirdly, the stratigraphic forward modeling results were resampled into the geological model, a 3D reservoir probability distribution model is established from trend modeling to quantitatively characterize the spatial distribution of sand bodies. Finally, the sandstone distribution simulation results were transformed into quantitative control constraints for 3D geological facies modeling. Thus, the new approach significantly promotes the facies model quality and provides robust results for petrophysical property models.

Integration of stratigraphic forward modeling with 3D geological modeling can effectively solve the problem of reservoir characterization in an early stage of oilfield development through the interaction of the dual model coupling. This method has unique advantages in the reservoir research in the area with fewer data and great variation of sand.
Machine Learning for Detecting Stuck Pipe Incidents: Data Analytics and Models Evaluation
Authors: Alshaikh Abrar , Magana-Mora Arturo , Gharbi Salem Al , Al-Yami Abdullah
Published: April 2019

The earlier a stuck pipe incident is predicted and mitigated, the higher the chance of success in freeing the pipe or avoiding severe sticking in the first place. Time is crucial in such cases as an improper reaction to a stuck pipe incident can easily make it worse. In this work, practical machine learning, classification models were developed using real-time drilling data to automatically detect stuck pipe incidents during drilling operations and communicate the observations and alerts, sufficiently ahead of time, to the rig crew for avoidance or remediation actions to be taken.

The models use machine learning algorithms that feed on identified key drilling parameters to detect stuck pipe anomalies. The parameters used in building the system were selected based on published literature and historical data and reports of stuck pipe incidents and were analyzed and ranked to identify the ones of key influence on the accuracy of stuck pipe detection via a nonlinear relationship. The model exceptionally uses the robustness of data-based analysis along with the physics-based analysis.

The model has shown effective detection of the signs observed by experts ahead of time and has helped with providing enhanced stuck pipe detection and risk assessment. Validating and testing the model on several cases showed promising results as anomalies on simple and complex parameters were detected before or near the actual time stuck pipe incidents were reported from the rig crew. This facilitated better understanding of the underlying physics principles and provided awareness of stuck pipe occurrence.

The model improved monitoring and interpreting the drilling data streams. Beside such pipe signs, the model helped with detecting signs of other impeding problems in the downhole conditions of the wellbore, the drilling equipment, and the sensors. The model is designed to be implemented in the real-time drilling data portal to provide an alarm system for all oil and gas rigs based on the observed abnormalities. The alarm is to be populated on the real-time environment and communicated to the rig crew in a timely manner to ensure optimal results, giving them sufficient time ahead to prevent or remediate a potential stuck pipe incident.
Structure and Inhibition of the Indolizine Derivative: New Concept of High-Efficient Corrosion Inhibitors for Acidizing
Authors: Wang Renzhuo , Yang Zhen , Chen Wuhua , Wang Yefei , Ding Mingchen , Zhan Fengtao
Published: April 2019

Among the numerous corrosion inhibitors for acidizing, the propargyl alcohol, with great expense and high toxicity, is often added as an important synergistic component. In this work, novel indolizine derivative high-effective inhibitor for acidizing was introduced. The indolizine derivative could exhibit an excellent protection performance at a much lower concentration without the synergism of the poisonous propargyl alcohol. The two inhibitive indolizine derivatives in this paper were synthesized easily from Benzyl Quinolinium Chloride (BQC, known as the a commonly used key component of acidizing inhibitor) via 1,3-dipolar cycloaddition reaction. The indolizine derivatives were purified by the column chromatography and the structure were characterized by NMR and elementary analysis etc.

The inhibition performance of the BQC, propargyl alcohol and the indolizine derivatives in 15 wt.% HCl and 20 wt.% HCl for N80 steel was investigated by weight loss test and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The conclusion obtained from the electrochemical tests is in accordance with the results of gravimetric test. It is amazing to notice that the derivative could exhibit a much better anti-corrosion performance than its precursor BQC and propargyl alcohol in the abserence of the poisonous propargyl alcohol.

Compared with BQC, the active adsorption sites are reinforced and strengthed in indolizine derivatives, and therefore, the inhibitor would fasten the steel surface more stronger. The firmly adsorbed inhibitors would prohibit the steel from the contact of acid. Indolizine derivative is presented as a new concept of effective acidizing inhibitor for the first time in this paper. It may offer a new method for the corrosion prevention in acidification engineering.
A Data Driven Approach of ROP Prediction and Drilling Performance Estimation
Authors: Han Jiahang , Sun Yanji , Zhang Shaoning
Published: April 2019

Given the expense of drilling in resource development, explore the optimal drilling operations, especially improve the rate of penetration (ROP), has become increasingly important. The prediction of ROP is challenging due to the complex bit and rock interactions. Several experience based models have attempted to predict ROP, but few of them can have excellent estimations.

In this paper, a new ROP prediction methodology is developed using machine learning techniques. The booming computation capacity and large volume of data provide a new way to solve the problems. In this paper, wells from southern China have been used to demonstrate our approach. Well logging, mud logging data, geological information, daily well reports, and many other data have been included for the model development. Parameters which have been previously considered irrelative to ROP calculation show their impacts in the model.

The machine learning approaches bring new insights into the ROP prediction. Comparing with the conventional approach, our method consider drilling as a continuous procession. ROP at current time relates to the drilling rate in previous time step. In our case, the model improves ROP estimation accuracy. In addition, engineers can use this tool to arrange better drilling plans during operation. Dive deep into the data, the acceleration and deceleration of ROP showed close relationship to WOB and mud properties, improve the mud rheology and operation strategies can keep the ROP in a optimal range which may enhance the drilling efficiency.

With the assistance of machine learning techniques, a new method of ROP prediction has been developed. Comparing with the conventional approaches, this method considers more parameters and improves accuracy. Factors that may enhance the drilling bit performances were also explored. This new data driven method can be beneficial for drilling efficiency.
An Integrated Approach to Well Leak Diagnostics: Case Study of the Successful Application of the Latest Leak Detection Technology and Interpretation Offshore Timor Sea, South East Asia
Authors: Imrie Andrew , Negenman Brendon , Lee Chung Yee , Iyer Mahadevan S. , Parashar Sarvagya , Shata Mohamed Raouf , Helton Sean
Published: April 2019

The identification of low-rate leaks along with low annular-pressure buildup rates in any type of completion presents challenges in the well-integrity domain. This paper emphasizes the importance of understanding the well-diagnostic problem to determine feasibility, isolate interest zones, enhance stimulation strategies, and ultimately optimize the acquisition of high-resolution acoustical data from the wellbore with a latest-generation advanced leak-detection tool.

This case study discusses the methodology that underlies the successful determination of the depths and the radial locations in the outer casing strings of multiple leaks in an offshore well. In the study presented, emphasis had been placed on the job planning to provide adequate or substantial leak stimulation for the accurate determination of the leak points in terms of radial distance away from the tool axis within the wellbore. Rather than a shut-in and flowing or venting acquisition, it was proposed that the optimal method for the successful determination of an outer casing string leak involved invoking a range of flow rates and, therefore, acoustic levels, across an extended period. The study also demonstrates the advantages of integrating acoustic-based tools with conventional production logging tools.

Two outer string casing leaks with annulus to formation communication areas were identified from high-resolution leak-detection logging coupled with conventional pressure and temperature measurements. The interpretation process included the computation of a 2D radial map of the flow activity across each zone of interest. This process resulted in less ambiguity and clearer results obtained in real time during the acquisition. The location of each leak point was triangulated using an error-minimization algorithm from the received acoustic waveforms at the tool receiver array. Further, the optimized stimulation strategy enabled leak-stimulation responses to be tracked in the computed power spectral density (PSD) at each leak. This process enabled the operator to promptly move on with the well abandonment strategy without waiting for further data analysis.

Attention to detail from the outset and a complete understanding of the well and its annular pressure and fluid behavior enabled an optimized and focused electric line diagnostic strategy to be used. The use of high-resolution acoustic data from an advanced leak-detection tool with an array of hydrophones ensured that the multiple leak locations were identified and characterized.