bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine Learning Overcomes Challenges of Selecting Locations for Infill Wells
Authors: Wilson Adam
Published: October 2018

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 190101, “Infill-Well Location-Selection Procedures in Lost Hills Using Machine Learning,” by T.H. Kim, SPE, D.J. Crane, and E.F. Grijalva, SPE, Chevron, prepared for the 2018 SPE Western Regional Meeting, Garden Grove, California, USA, 22–27 April. The paper has not been peer reviewed.

For most conventional reservoirs, numerical simulation is successful in forecasting and extracting valuable information regarding optimal locations for new wells. The results of numerical simulations for the Lost Hills field, however, were not successful because of the special characteristics of its diatomite reservoirs—low permeability but high porosity, weak rock strength, and strong imbibition. Machine learning (ML) has been considered because it does not require specific physical models but can provide good estimations with enough data.

Introduction

The Lost Hills field is approximately 45 miles northwest of Bakersfield, California, USA. It was discovered in 1910, and hydraulic fracturing was introduced in the late 1970s. Waterflooding was introduced in 1992 and has become the main production method. The main reservoir rock type is diatomite, which is formed by the accumulation of diatoms, single-cell organisms. The aver-age pay thickness is approximately 800 to 1,000 ft, and depth to the reservoir base is approximately 2,000 ft. The estimated original oil in place is more than 2 billion bbl.

ML Algorithms and Voronoi Diagram

K-Means Clustering. K-means clustering is one type of unsupervised learning algorithm. As opposed to supervised algorithms, unsupervised learning algorithms do not need answers supplied. K-means clustering algorithms identify the members of each cluster by iterating the following steps:

Generate the centroid of each of the clusters randomly. The number of clusters, K, is a user input.

Each data point is assigned to its nearest centroid so that K clusters are created.

The new centroid of each cluster is updated so that the Euclidian distances to the centroid are minimized.

Repeat Steps 2 and 3 until convergence has been reached.

Support Vector Machine (SVM). SVM is a supervised ML algorithm. For supervised learning algorithms, the answers must be supplied to train and build a predictive model. SVM has two main applications, classification and regression, and classification is used in this study.

SVM builds a hyperplane or set of hyperplanes that separate data into groups (classification) or form a regression line; a hyperplane is a subspace of one dimension less than its ambient space (e.g., a plane in 3D space). Fig. 1 shows an example of classification in 2D space. The red line is a hyperplane set to have the maximum gap between two classes. Data vectors in circles are borderline members and are called support vectors. When building a hyperplane is difficult, data are mapped into a higher-dimensional space to facilitate finding a hyperplane.
Dynamic Steam-Trap-Control Simulation Technique: Formulation, Implementation, and Performance Analysis
Authors: Heidari M.. , Nghiem Long X.
Published: October 2018

Steam-trap subcool is a technique that is used to maintain the energy efficiency of the steam-assisted-gravity-drainage (SAGD) process by most heavy-oil producers in Canada. The concept is rather simple (i.e., create a liquid pool around the production well to prevent steam from escaping from the steam chamber into the production well). A numerical steam trap based on a thermodynamic approach was implemented by Edmunds (2000), and it has been used in simulations with different types of wellbore models in commercial codes. In this approach, a thermodynamic relationship is solved as a well-residual equation to guarantee that the bottomhole temperature (BHT) is less than the saturation temperature of water at the hottest location along the wellbore. The location of the hottest spot along the wellbore is static in time. Steam trap is a dynamic process, and inflow temperatures can vary significantly along the wellbore according to the local fluid and rock properties along the well. It is highly possible that the location of the hottest spot along the well changes frequently with time during the SAGD operation.

In this study, the simulation of a dynamic steam-trap-control technique is provided. The location of the hottest spot along the wellbore is scanned at every timestep. Severe numerical instabilities are observed when the thermodynamic approach is used. A new constraint based on the total production rate at reservoir condition is introduced. Details of the mathematical formulation and the numerical behavior of the new method are discussed in this paper. Several real field models with different wellbore designs (multiple tubing strings) are simulated, and the results of the new approach are compared with the thermodynamic approach. Simulation results show that the numerical performance of this new approach is significantly more stable. We also compared the run time of simulation between cases with new well constraint and thermodynamic steam-trap control, and results show a significant improvement in simulation run time.
Improving Casing Integrity With Induction Brazing of Casing Connections
Authors: Ernens D.. , Hariharan H.. , van Haaften W. M. , Pasaribu H. R. , Jabs M.. , McKim R. N.
Published: October 2018

Brazing technology allows metallurgical joining of dissimilar materials using a filler material. In this paper, brazing technology applied to casing connections is presented as an enhancement of existing (premium) connections and/or a replacement of metal/metal seals. The initial application was triggered by challenges with mechanical and pressure integrity after the expansion of casing connections. Creating a strong bond between the pin and the box could resolve this and remove the need for a metal/metal seal. Brazing was selected because of the combination of ductility and high bond strength and the relatively fast process to create the bond. The brazing process or the temperature/torque/time (TTT) process is performed using regular casing connections, a filler material deposited by flame spray and a flux. Two processes were developed, one for expandable (VM 50) grade material and one for quenched and tempered grade material. A rig-ready (Class 1, Division 1) prototype brazing system was developed consisting of an induction coil as the heat source, an environmental chamber to shield the hot work, and a modified power tong to provide torque. The results of a series of brazing trials on 8⅝- and 9⅝-in.-casing connections are presented. The brazed connections were subsequently capped, end-pressure tested, expanded (when applicable), and load cycled. It is concluded that both processes produced leak-tight casing connectors before and after expansion (when applicable), as shown by full-scale tests.
Comparative Study of Oil-Dilution Capability of Dimethyl Ether and Hexane as Steam Additives for Steam-Assisted Gravity Drainage
Authors: Baek Kwang Hoon , Sheng Kai , Argüelles-Vivas Francisco J. , Okuno Ryosuke
Published: October 2018

Dimethyl ether (DME) was investigated as a potential additive to steam to improve steam-assisted gravity drainage (SAGD) in a previous simulation study. The main objective of this research is to compare DME with n-hexane in terms of the capability of viscosity reduction for Athabasca bitumen. In addition, new experimental data are presented for bubblepoint pressures, densities, and viscosities of Athabasca bitumen and its mixtures with DME and n-hexane.

Results show that DME results in slightly higher viscosity than n-hexane when they are mixed with the same Athabasca bitumen at a given pressure, temperature, and molar concentration. For example, the equimolar mixture of DME with Athabasca bitumen is 79 cp, and that of n-hexane with the same bitumen is 49 cp at 328 K and 60 bar. However, the two solvents are equivalent as diluent at temperatures higher than 380 K. For example, the difference is approximately 1 cp at 382 K and 35 bar between the equimolar mixture of Athabasca bitumen with DME and that with n-hexane.

The viscosity data measured for bitumen/n-hexane mixtures and bitumen/DME mixtures in this research were correlated with three different viscosity models: a modified Arrhenius model, the power-law model, and the Walther (1931) model. The viscosity data were well-correlated with the modified Arrhenius model, but not with the original Arrhenius (log-linear mixing) rule. The modified Arrhenius model can be used directly with a commercial simulator.

Liquid/liquid separation for solvent/bitumen mixtures, which occurred for n-butane/Athabasca bitumen in Gao et al. (2017), was not observed for any of the DME/bitumen and n-hexane/bitumen mixtures in this research. The highest solvent concentration in this study was 80 mol% DME for the DME/bitumen system and 92 mol% n-hexane for the n-hexane/bitumen system.
Development and Application of a Fully Implicitly Coupled Wellbore/Reservoir Simulator To Characterize the Transient Liquid Loading in Horizontal Gas Wells
Authors: Tang Hewei , Rashid Hasan A.. , Killough John
Published: October 2018

Liquid loading is a challenging issue in most mature gas fields. The dynamic interaction between wellbore and reservoir when liquid loading happens cannot be comprehensively simulated by a single wellbore simulator or a single reservoir simulator. In this paper, we develop a fully implicitly coupled wellbore/reservoir model to characterize the flow transients in liquid-loaded horizontal gas wells.

We fully couple a wellbore model with an in-house reservoir simulator based on the control-volume finite-difference method. Wellbore transient material-balance equations and mixture momentum-balance equations are solved simultaneously with the reservoir equations to obtain pressure, mixture velocity, and phase holdup in each wellbore segment. Also, we propose a modified drift-flux model that is capable of predicting the flow-regime transition for different pipe inclinations from vertical to horizontal. The modified drift-flux model is integrated in the coupled wellbore/reservoir simulator to characterize the two-phase flow in horizontal wellbores. We validate the coupled wellbore/reservoir model with a commercial multisegment wellbore (MSW)/reservoir simulator. The revised drift-flux formulation not only matches a commercial simulator in production forecast and wellbore pressure, but also predicts the subsequent unstable liquid production caused by flow-regime transitions. For a synthetic field-scale case, the new model predicts gas production that lasts 23 days longer than the prediction of a commercial simulator.

This paper extends the capability of a fully implicitly coupled wellbore/reservoir simulator to simulate the transient liquid-loading phenomenon. The model can serve as a promising tool for gasfield development.
Tunnel-Length Modeling for Coiled-Tubing-Acid-Tunneling Stimulation in Carbonate Reservoirs
Authors: Livescu Silviu , Craig Steven , Aitken Bill
Published: October 2018

A coiled-tubing (CT)-acid-tunneling-stimulation technique has been successfully applied in the preceding 15 years on limestone and dolomite reservoirs around the world (the Middle East, southeast Asia, North America, South America, and Europe). Several case histories were presented in the past showing that this technique might bring significant benefits over other carbonate-stimulation methods in openhole wells. In this paper, the parameters affecting the predicted and achieved tunnel lengths are discussed for the first time.

The acid-tunneling technique consists of pumping hydrochloric acid (HCl) through conventional CT and a bottomhole assembly (BHA) with jetting nozzles to create (without drilling) stable drainage holes (tunnels) into the reservoir pay zone. The BHA also includes a special kickoff tool, with two pressure-activated bending joints, that controls the tunnel-creation direction. The acid that is not consumed during the main tunneling process leaks into the reservoir rock, creating wormholes that improve the connectivity between the reservoir and the wellbore and positively influence well production. This acid-tunneling technique can potentially create numerous tunnels with different depths. The optimization of the tunnel-creation-depth selection is made by production-software simulation using such critical information as the well parameters (trajectory and size), available logs (image, resistivity, caliper, drilling), and past reservoir information.

The results from many field case histories involving the CT acid-tunneling technique from around the world were presented previously. However, many questions remain unanswered regarding the actual downhole tunnel-initiation/creation process. In this study, a detailed discussion of acid-tunneling modeling is included to answer some of those questions. The parameters affecting the predicted tunnel lengths and the parameters that could be monitored or adjusted to create the tunnels smoothly are discussed.

This paper describes the CT acid-tunneling technology and discusses some of the most important questions regarding downhole CT acid-tunneling creation. The acid-tunneling-technique performance and benefits confirmed during field operations are presented.
Darcy-Scale Simulation of Boundary-Condition Effects During Capillary-Dominated Flow in High-Permeability Systems
Authors: Andersen Pål Ø. , Brattekås Bergit , Nødland Oddbjørn , Lohne Arild , Føyen Tore L. , Fernø Martin A.
Published: October 2018

We present numerical interpretations of two experimental sets of spontaneous-imbibition tests with combined cocurrent/countercurrent flow in high-permeability, unconsolidated sandpacks. The experiments were conducted using the two-ends-open free-spontaneous-imbibition (TEOFSI) boundary condition, in which one end face was in contact with the wetting (W) phase and the other with the nonwetting (NW) phase. The simulations quantified the impact from boundary-condition effects during capillary imbibition in the low-capillary sandpacks; the flow resistance in the outlet filter controlled imbibition rates, end recovery, and countercurrent production in tests with high NW-phase viscosity. A hydrostatic water column of a few centimeters at the W-phase end face also affected the imbibition process. Numerical and analytical solutions provided insight into when such boundary effects become important. In particular, the observed linear recovery with time and variations in time scale could not be explained by conventional modeling, but were captured by incorporating a thin, low-permeability filter into the models. For high-viscosity NW-phase tests with a low-permeability filter, countercurrent production is strongly enhanced and controlled by the capillary backpressure (CBP).
System Run Life Improvement for Rod Driven PCP in High Deviation Well
Authors: Khadav Sandeep , Agarwal Shubham , Kumar Piyush , Pandey Nimish , Parasher Arunabh , Kumar Sanjeev , Agarwal Vinay , Tiwari Shobhit
Published: October 2018

Bhagyam is a shallow onshore field in the northwestern region of India developed by Cairn Oil & Gas, a vertical of Vedanta Limited in two different phases with over 106 oil-producers with deviations as high as 70° and Dog Leg Severity (DLS) up to 7 deg/30m. Rod driven Progressive Cavity Pumps (PCP) were selected as the primary mode of artificial lift. The produced fluid properties which included high wax content and variable fluid viscosity ranging up to 250 cP were the main drivers in the selection of PCPs. A total of 250 unique installations of PCP systems have been completed in over 100 wells. These systems have accumulated a cumulative run-time of over 150,000 days over a total period of more than 2550 days from first installation, with an average tubing-pump system run-life of 600 days.

A major disadvantage of using a rod driven artificial lift system is metal to metal wear between rod and the tubing during operation. This metal wear in rod and tubing results in string failure, increasing costly well interventions and increased system downtime. This paper will demonstrate through specific case studies how pump operating parameters and well design were optimized over time to reduce well interventions and operating expenditures (OPEX).

A centralized data base with real time data configured with a predictive analytical model and automated performance analyzer have enhanced PCP monitoring and troubleshooting. Predictive modelling has improved preventative maintenance such as preemptive rod change outs which greatly reduced the number of rod failures increasing system uptime. In conjunction with joint industry program, detailed root-cause analysis supported with Dismantle Inspection and Failure Analysis (DIFA) laid the foundation for operational and design improvements in PCP operated wells.

Some of the recent improvements employed in system design for PCP operated wells are: Installation of through tubing PCP on an insertable anchor/pump sitting nippleInstallation of packer with completion stringUse of peened rods with molded guidesSnap-on and spin thru guided rodsInstallation of externally flushed hollow rod stringReplacement of conventional vam top tubing with boronized tubingInstallation of high volume PCPs.
Focus on Reducing Cost of Ownership Drives the Development of the 4th Generation Drill Pipe Connection Design
Authors: Plessis Guillaume , Muradov Andrei , Morgan Dan , Brock Jim , Primeaux Alan
Published: October 2018

The past three decades saw the introduction of several generations of double-shouldered drill pipe connections with performance as a primary development focus. The record extended-reach drilling (ERD) wells could not have been drilled and completed without these technological advancements, which brought more torque, enhanced hydraulics, and greater reliability to satisfy drillers’ needs. The improved performances of these technologies were so enabling that the associated repair costs were deemed acceptable.

When these same connections started to be used on land rigs to deliver wells in a factory drilling fashion, where cost control is of higher importance, the cost of maintaining these premium connections started to become more of an issue. Therefore, it became obvious that a different approach was required to meet the combined need for both performance, as well as a lower total cost of ownership post-acquisition.

A comprehensive two-year research and development (R&D) program was carried out to evaluate various design options. After a three-month field trial, the connection was released and has been used in the field since the second quarter of 2017.

The 4th generation double rotary-shouldered connection design provides benefits in addition to the previously seen improvements in torque, hydraulics, and streamlined profile. Specifically, the design optimizes the connection stresses, has broader tolerances for field damage, reduces the material loss on repairs, and provides greater connection ruggedness, all increasing field life and reducing operating cost.

The 4th generation double-shouldered connection was used in various onshore and offshore fields, accumulated a high number of drilling hours and has been inspected multiple times.

This paper demonstrates the performances of this new rotary-shouldered connection, its ruggedness and suitability for use on various kinds of rigs, and confirms the lower repair rates and reduced operational cost of ownership. As rental strings are rotated from rig to rig, they are prime candidates for evaluating these factors. Data compares the field damage and repair frequency of this new connection with earlier generation connection designs.
Zonal Isolation in Horizontal Configurations: Dynamic Cement Placement Approach Applied in Argentina, a Case Study
Authors: Ficetti S. , Silva P. , Revilla R. , Torgau N. , Carestia N.
Published: October 2018

The increasing energy demand has led shale unconventional reservoirs to become a focal point for operators worldwide. Over the past decades, several technological advances were conveyed to drilling and completing horizontal geometry wells in which massive hydraulic fracture treatments are deployed to improve production of these reservoirs.

Argentina has one of the largest shale-stored hydrocarbon reserves in the world and has become one of the leading countries in the exploration, appraisal, and development of unconventional reservoirs. The number of horizontal shale wells drilled in the country increased over the past decade, generating the need to find solutions to cement horizontal laterals and achieve the required zonal isolation for the normal completion and production of these wells, preserving well integrity.

Based on the difficulties encountered to cement these horizontal wells, such as channeling and differential fluid velocities, among others, the need to implement casing rotation while cementing was considered. This mechanical method has remained locally as one of the least accepted solutions because of the fear that the high torques during the operations would cause casing failures.

In a recent unconventional campaign, casing rotation was applied during well conditioning and along the cementing operation. A sensitivity study to rotational speed was performed, and the cementing design was optimized with a new 3D annular displacement simulator (3D-ADS) that predicts annular flow in complex geometries, accounting for pipe movement. The well was cemented successfully, obtaining congruent results from comparing bond logs and fluid placement simulations.

This study defines some of the factors contributing to a successful cementing job in a horizontal geometry, the aspects to be analyzed from the cementing perspective when rotating casing to aid in mud displacement, and the evaluation of the wells cemented under these circumstances compared to the simulated results predicted during the design phase of the well.
Interpretation of Nuclear-Magnetic-Resonance Response to Hydrocarbons: Application to Miscible Enhanced-Oil-Recovery Experiments in Shales
Authors: Dang Son T. , Sondergeld C. H. , Rai C. S.
Published: October 2018

Estimation of total reserves in shale/gas and shale/oil reservoirs is challenging but critical. Different logging tools and core-evaluation procedures are used to address this challenge. Nuclear magnetic resonance (NMR) plays a vital role in understanding fluid content, rock/fluid interaction, and determination of pore-body-size distributions. Hydrocarbon (HC)-hosting pore systems in shale includes both organic and inorganic pores. Recoverable HCs include bitumen and light HCs. Their relative fractions are strongly dependent on thermal maturity. Regardless of detailed chemical characterization, “bitumen” is simply defined on the basis of mobility in this study. The apparent mobility of HCs depends on fluid composition, solubility, and reservoir temperature. Historically, NMR laboratory-calibration measurements (nominally, 2-MHz) on core are conducted at room temperature (25–35°C). This study highlights the importance of running NMR tests at reservoir temperature. Experiments were performed for both bulk fluids and fluid-saturated rock samples.

The results show that, at a specific temperature, NMR responds only to the fraction of HCs present in the liquid phase. For routine NMR measurement, at 31°C, only the relaxation signals of compounds more volatile than C17 are acquired. Thus, the C17+ fraction would be invisible to NMR at room temperature, but perhaps not at reservoir temperature. This is critical to the interpretation of NMR log response within the early oil and condensate windows, in which C17+ can be a major fraction. Thus, engineers can underestimate movable HCs by using routine core data as a basis for interpretation.

On the basis of NMR experiments for several oil samples, we observed that the T1–T2 distributions depend on the overall composition of total HCs and effective mobilities. The results also show that, in the case when both light and heavy HC fractions coexist in a single phase, they do not appear as different clusters in a T1–T2 distribution map. NMR parameters were used to monitor the amount, composition, and effective mobility of remaining HCs after each injection and discharging cycle, during miscible enhanced-oil-recovery (EOR) huff ’n’ puff experiments on Eagle Ford samples.
Rapid Evaluation of the Permeability of Organic-Rich Shale Using the 3D Intermingled-Fractal Model
Authors: Li Caoxiong , Lin Mian , Ji Lili , Jiang Wenbin , Cao Gaohui
Published: October 2018

Shale possesses abundant micro/nanopores. Most micro/nanopores that exist in organic-rich shale are organic pores and mainly developed in organic matter. The pore distribution in matrix space significantly affects gas percolation and diffusion. Pore-size distribution possesses a self-similar, or fractal, property. The pore space and gas permeability of shale can be easily rebuilt and evaluated, respectively, using fractal theory. In this work, a 3D intermingled-fractal model (3D-IFM) is successfully built using scalable scanning-electron-microscopy (SEM) images of shale samples. 3D-IFM is made up of several components, including organic pores in organic matter and in pyrites, inorganic pores, slits, and matrix. An improved pore-connective-calculation method is also introduced to evaluate the apparent gas permeability of the shale model. The proposed 3D-IFM rapid-permeability-evaluation method for organic-rich shale is valid and useful and considers the main components of shale. This method can rapidly evaluate apparent gas permeability and simplify the apparent-gas-permeability-calculation process. Thus, the method provides a promising means of rapidly evaluating apparent gas permeability.
Integration of 4D Seismic in Steam-Assisted-Gravity-Drainage Reservoir Characterization
Authors: Hadavand Mostafa , Carmichael Paul , Dalir Ali , Rodriguez Maximo , Silva Diogo F. , Deutsch Clayton V.
Published: October 2018

4D seismic is one of the main sources of dynamic data for heavy-oil-reservoir monitoring and management. 4D seismic is significant because seismic attributes such as velocity and impedance depend on variations in reservoir-fluid content, temperature, and pressure distribution as a result of hydrocarbon production. Thus, the large-scale nature of fluid flow within the reservoir can be evaluated through information provided by 4D-seismic data. Such information may be described as anomalies in fluid flow that can be inferred from the unusual patterns in variations of a seismic attribute. During steam-assisted gravity drainage (SAGD), the steam-chamber propagation is fairly clear from 4D-seismic data mainly because of changes in reservoir conditions caused by steam injection and bitumen production. Anomalies in the propagation of the steam chamber reflect the quality of fluid flow within the reservoir. A practical methodology is implemented for integration of 4D seismic into SAGD reservoir characterization for the Surmont project.
A New Analytical Solution of the Triple-Porosity Model for History Matching and Performance Forecasting in Unconventional Oil Reservoirs
Authors: Qiu Kaixuan , Li Heng
Published: October 2018

Production data from hydraulically fractured horizontal wells in ultralow-permeability reservoirs have been observed to exhibit a half-slope straight line on a log-log plot of rate vs. time. Using these observations, many analytical models of linear flow have been developed to analyze the well performance in these reservoirs. However, it is relatively complicated to solve these models with the Laplace transform and numerical inversion. In this paper, a new analytical solution of a triple-porosity model is derived for unconventional oil reservoirs. The partial-differential equations (PDEs) are transformed into ordinary-differential equations (ODEs) by integration, instead of the Laplace transform. A rate-vs.-time solution in real-time space can be obtained, bypassing the numerical inversion for the Laplace transform. Our model is validated by comparison with both the numerical-model and Laplace-transform solutions. The physical meanings of the model parameters are analyzed through sensitivity analysis. The new model is then applied to field-production data for history matching and forecasting. Besides matching the production data, the pore volume (PV) of the matrix and fracture media can be estimated, which helps quantitative analysis of unconventional reservoirs.
A Comprehensive Work Flow To Characterize Waterflood-Induced Fractures by Integrating Real-Time Monitoring, Formation Test, and Dynamic Production Analysis Applied to Changqing Oil Field, China
Authors: Wang Yang , Cheng Shiqing , Zhang Kaidi , He Youwei , Feng Naichao , Qin Jiazheng , Luo Le , Yu Haiyang
Published: October 2018

It is well-known that water injection may induce formation fracturing in tight reservoirs. Especially when the field-geology condition is complex and the waterflood-induced fractures (WIFs) are not well-identified in time, the induced fractures can be of the same order as the well spacing, which has a significant, and generally undesired, impact on both areal sweep and vertical conformance. Therefore, the onset of WIFs must be identified in a timely manner, and the waterflooding performance must be evaluated comprehensively to formulate an appropriate strategy over time.

A new work flow, containing analytical/semianalytical, statistical, and numerical techniques that are based on flow-rate/BHP and formation-testing data, is applied to identify the WIFs, diagnose waterflooding direction and front distribution, analyze interwell connectivity, and interpret abnormal bottomhole-pressure (BHP) behaviors in the Changqing Oil field. The work flow includes three modules: First, real-time monitoring and analysis, including modified Hall plot, evolving skin analysis, and injection/fracturing index methods, are used to identify the start of WIFs. Then, the formation-testing module, consisting of step-rate test (SRT), radioactive-tracer logging, and passive seismic method, is applied to investigate the formation-fracturing pressure, and uneven waterflooding performance in the areal and vertical directions. On the basis of the two former modules, we adapt the third module, which includes injector/producer relationships (IPRs) and the constrained multiple-linear-regression (MLR) method, to quantitatively investigate the waterflooding direction by injection/production rates. A new model—injection well with waterflood-induced fracture (IWWIF)—is proposed to characterize the abnormal BHP behaviors considering the properties variation (shrinking fracture length and decreasing fracture conductivity) of WIFs during the falloff period.

Compared with an individual method, the ITD (which is the abbreviation of WIF identification, formation testing, and dynamic production analysis) work flow is developed to obtain a comprehensive and deep understanding of waterflooding performance. The main emphasis of this study is to integrate different approaches to address the key uncertainties rather than analyze each data source individually. On the basis of the results obtained by this work flow, the operators can make a more-proactive and -reasonable decision on waterflooding management. The work flow proposed in this paper gives a useful guidance in short- and long-term waterflooding management in tight reservoirs.
Theoretical Study of Tool-Face Disorientation Mechanisms During Slide Drilling and Correction by Surface-Rotation Pulses
Authors: Wang Xueying , Ni Hongjian , Wang Ruihe , Wang Peng , Zhang Lei
Published: October 2018

Tool-face control is an important issue when drilling directional wells with steerable motors. Although extensive knowledge about tool-face orientation is available, the mechanisms of tool-face disorientation during slide drilling are not completely understood. Surface-rotation pulses can correct tool-face orientation (Maidla and Haci 2004), but the underlying mechanism, in our view, remains unclear. This paper proposes a drillstring model to analyze the mechanisms underlying tool-face disorientation and correction.

Our drillstring model is based on the finite rigid-body assumption with a mixed friction model that incorporates Stribeck's friction curve. The simulation results indicate that tool-face hysteresis caused by the difference in the higher loading rate and lower unloading rate of reactive torque is an essential factor in tool-face disorientation. In addition, a harder formation is more prone to inducing tool-face disorder. The process of tool-face correction can be divided into three stages, and the position of the vanishing point of reactive torque determines the effectiveness of the surface-rotation pulse. The tool face turns clockwise only if the applied rotation pulse drives the vanishing point of reactive torque downward to the bit.

The simulation results and analysis are useful for understanding drillstring behavior during slide drilling and further improving the efficiency of tool-face control.
Overview of Industry Advancements in Environmental Awareness
Authors: Haut Richard , Wilcox Andra , Williams Tom , Burnett David
Published: October 2018

For the past fifteen years, industry, academia, government, environmental organizations and other stakeholders have worked together in a collaborative program to provide unbiased science to address environmental and societal issues associated with oil and gas activities. The research team has performed over 40 field trials related to land, water and emissions measurements. Case studies and specific examples on advancements in technologies and processes that have addressed land, emissions, water, stakeholder engagement, and other aspects are discussed. Also discussed is internal progress within industry to ensure that the workforce develops a culture of environmental awareness. Evolvement, aided by this collaborative effort, has been substantial. New technology developed has reduced land impacts through extended reach and horizontal drilling techniques, implementing new, energy-efficient rigs, and improving logistics coordination. Noise and lighting have also been addressed. Emissions have been reduced throughout drilling, completion and production operations through reduced drilling times, electrification of various processes, and flaring reduction. Operators have increased the recycling and use of produced water throughout completion operations and are implementing voluntary water conservation efforts. Public engagement by operators has increased acknowledging that stakeholder engagement is an important aspect of how to address environmental concerns. The team has developed novel methods, for example the development of virtual sites using gaming software, to enable stakeholders to become aware of the importance that industry places on addressing environmental aspects. How industry has successfully communicated advances in environmental stewardship is also discussed.
Successful Hydraulic Fracturing Techniques in Shallow Unconsolidated Heavy Oil Sandstones Part 2: Multifracturing Job Performance
Authors: Zagrebelnyy Evgeniy , Martynov Mikhail , Konopelko Alexey , Kazakov Evgeny
Published: October 2018

There is not enough experience of hydraulic fracturing on unconsolidated low-temperature shallow formations, similar to the main development site of the East Messoyakhskoye field - PK1-3, was found in Russia. Test fracturing was performed on directional and vertical wells in the pilot works in 2017 and the main conclusions were drawn:Approve technological capability of hydraulic fracturing on unconsolidated and high-permeability heavy oil reservoirApprove creating traditional vertical fracture by geophysical methods and by the results of productionValue of fracture height by different methods of mapping fracture geometry are semi-comparable, which makes it possible to estimate the averaged value of each parameterPerformed complex of geophysics logging allows to estimate in technological efficiency of hydraulic fracturingPerformed complex of laboratory studies of various chemical compound hydraulic fracturing fluids on the core material made it possible to select the optimal compound with minimal negative impact on the formationStep-by-step method increase of the aggressiveness of the treatment designs allowed the accident-free implementation of pilot works and estimate of possible aggressiveness to tip screen out (TSO)The productivity gains resulting from the development and operation of the wells after the fracturing allow to adapt the result to the MHF in horizontal wells with the expected productivity gain of 40%Limite fracture height growth is achieved by planning the optimal injection design, but it is not always possible. If gas-oil contact is near, it is difficult to control the geometry of the fracture, which led to the limitation of replicating the fracturing in water-oil zones without gas cap.
Ahead of the Bit Pore Pressure Prediction under Centroid Effect Conditions Using Express Seismic Processing Results for Exploration Drilling in the Caspian Sea
Authors: Smirnov Nikolay , Kerusov Igor , Aristarkhov Anton , Sokolova Maria , Evmenov Nikolay
Published: October 2018

For the offshore prospecting and appraisal well drilling optimization, an approach was proposed, included Pore Pressure prediction based on 2D processing of a seismic surface data. This approach was used for timely detection of sharp changes in Pore Pressure with depth, under expected «centroid» effect for a well construction in the waters of the Caspian Sea.

At the initial stage, an acoustic inversion of 2D seismic data wascarried out. Based on the obtained acoustic impedance section and seismic velocities, after a deep migration, Pore Pressure forecast was conducted for the well area. Pore Pressure was restored for the offset well and relations between effective stresses and seismic inversions results were identified for different facies. Together with the geomechanical support, regular velocity-depth model updating process was realized, involving log and well data from drilled section.

Using the velocity-depth model, updating process and continuous support, Pore Pressure forecast was successfully implemented in the intervals with sharp pressure variations. Bottom-hole updates were carried out in the critical further drilling intervals using updated formation velocities and seismic attributes, to the depth of next drilling section. In real time, the pronounced regional centroid effect was confirmed and successfully passed. Directly during the drilling, casing depths were corrected, mud weight values and equivalent circulation densities were controlled in safe ranges. In this work, regional centroid effect was predicted and verified for the Caspian Sea area.

The completed project demonstrates the successful application of a process involving tomographic update of velocity-depth model and continuous Pore Pressure forecast for optimization and increasing offshore prospect well drilling safety. This approach is critical for successful well construction under centroid effect, particularly, in the Caspian Sea area.
Reliable Detection and Power in an Electronic Sliding Sleeve Multistage Completion System
Authors: Walton Zachary , Fripp Michael
Published: October 2018

A new electronic sliding sleeve has been developed for hydraulic fracturing that provides the operational efficiency of sliding sleeves while enabling an unlimited number of fracturing zones and eliminating the milling of the baffle seat. This system uses electronic sensors and battery power to determine when the next stage of the fracture is ready for pumping. The reliability of the sensors, electronics, and batteries must be addressed to achieve a reliable fracturing system.

Traditional sliding sleeves use a series of progressively smaller-sized balls that shift sleeves by landing on progressively smaller-sized baffles. The new electronic sliding sleeve has the intelligence to enable opening the sleeve without the use of progressively sized balls and baffles. The result is a monobore construction that enables stimulating an unlimited number of zones and simplifies well completion design and installation. The electronic implementation improves the mechanical reliability beyond mechanical monobore fracturing tools but introduces other concerns of reliability. This paper reports on the reliability testing of the electrical components including the electronics, sensor, and battery.

Electrical reliability of the new sliding sleeve was evaluated at high temperature, extended service duration, and high pump rates. The sleeve operates by counting the passage of frac balls and then shifting the sleeve when the programmed number of balls has passed. This battery-powered electronic sliding sleeve has an onboard sensor and processor equipped to count the balls. Once the programmed number of balls has been detected, an actuator commands the sleeve to shift. The sliding sleeve requires reliable operation of all components. A probabilistic model is used to account for stochastic variation in batteries and electronics. The magnetic sensors detected the frac ball over a wide temperature range and at flow rates ranging from near static to more than 100 bbl/min. The batteries were characterized for operating life, passivation, and self-discharge. Power consumption and reliability of the electronics were tested to accurately predict remaining operational life of the electronic system under a wide range of conditions. The resulting electronic sliding sleeve also increases mechanical reliability.

A programmable battery-powered electronic sliding sleeve increases flexibility, reliability, mechanical simplicity, and robustness for multistage hydraulic fracturing. This new fracturing system is particularly applicable in extended reach applications by offering an unlimited number of zones with a simple monobore construction.
Implementation of the Intellectual Gas Control System for Gas Lift Optimization at Orenburgskoe Oilfield
Authors: Ulyanov Vladimir , Kuchurin Alexey , Kibirev Evgeny , Gryzunov Andrey , Bak Viktor , Rymarenko Konstantin , Nukhaev Marat , Dadakin Nikita
Published: October 2018

The gas-lift operation is widely internationally used in the oil production. At present, this production method is used at the Orenburg oil and gas condensate field as one of its options—a natural-pressure gas-lift well operation method. The advantage of the natural-pressure gas-lift well operation method is a significant reduction in operating costs (electricity, electric submersible pump rent). At that both, new wells drilled into the gas cap and production wells where a breakthrough of gas has occurred can be used as a donor well. A feature that defines this operation method is a need for continuous control over pumping down each borehole. This is due to the fact that a donor well provides several producing oil wells with active gas, the operational parameters of these may significantly differ from each other. A system with automatic lock shield valves was adopted to automate the injection of gas in the Orenburg oil and gas condensate field, it allowed tuning up the injection, constantly monitoring and metering consumption of gas for each well.

This paper outlines the Gazpromneft-Orenburg experience in adopting an intelligent system for gas injection monitoring. It is described as a stage of a technical task preparation, conducting pilot runs at several wells, adjusting requirements to the equipment based on the results of pilot runs, full-scale implementation of the project at all wells of the deposit, optimization of gas-lift wells throughout the well stock.

The automated gas-lift process control system adopted at the Orenburg oil and gas condensate field allowed: collecting and processing information coming from primary transducer-converters;managing the actuators ensuring optimal well performance;operatively ensuring well operation mode alternations;accumulating the information received to gather statistical data and monitor the oil wells status.
Bringing the Sucker Rod Pumping Unit into the Classroom with the Use of the Internet of Things
Authors: Teodoriu Catalin , Pienknagura Erik
Published: October 2018

Artificial lift and particularly sucker rod pumping units are the most applied technologies for oil wells. While the equipment as such requires strong mechanical background, the use of the equipment remains solely the responsibility of petroleum engineers. Teaching them the working principles and functions of the equipment could be a challenging process when using only classroom related tools such as multimedia, short pieces of equipment, etc. As a response to this shortcoming, a new laboratory has been developed at the University of Oklahoma, which includes a large-scale pumping unit that is capable to be programed to simulate any situation in real time and use the Internet of Things to gather real time data and create tailored diagnostic tools that students and laboratory staff can utilize for many applications.

This paper focuses on the need to add a hands-on teaching experience to the classroom, and what type of data can be mined and used to accomplish specific objectives. It is required for our future petroleum engineers that they know how to apply basic industry principles and increase problem solving skills involving machinery. The proposed laboratory would be capable to deliver all standard monitored parameters of a sucker rod pumping unit to any classroom through a networked connection and allow the students to make decisions or experiment in real time with the setup. By being a large-scale setup, students can easily observe how the unit works, visualize downhole pumping operations, identify where the sensors are placed, and learn how to use raw data for any intended purpose. In other words, the entire artificial lifting process can be seen and operated from any classroom on campus remotely, and advanced analysis can be performed by the students or staff.