查看更多>>摘要：When producing from conventional fields,the well rates are primarily constrained by the production-system in the early years of the field-life,while later in the field-life the production rates are primar-ily constrained by the reservoir deliverability.For the post-plateau production period,the reservoir deliverability will no longer potentially exceed the production-system well-rate constraints.Tradition-ally,analytical equations are used in a nodal analysis method that balances the pressure at the well inflow point from the reservoir(inflow performance relationship;IPR)with the pressure required for the vertical lift performance(VLP;or vertical flow performance;VFP)from the same point upward.A faster and simpler approach is proposed in the present study.Whereas,the classical IPR solutions are based on a constant well-rate solution of the diffusivity equation,use of a constant bottomhole pressure assumption can bypass the need for nodal analysis type pressure matching solutions to obtain the well rate.Instead,the well rate can be directly computed from the pressure decline in the reservoir and any production system capacity constraint can be imposed on the theoretical well rate due to the reservoir quality.The merits of the new approach are explained and illustrated by way of a detailed production analysis case study using open-access data from the Volve Field(Norwegian Continental Shelf).In addition,the case study of the Volve Field wells demonstrates a new water-breakthrough analysis method.
查看更多>>摘要：Optimal and cost-effective drilling operations in extended-reach horizontal wells depend on efficient solid cuttings removal from the borehole.Several solids-suspended multiphase processes such as crude petroleum transportation,separation,and processing of oil and gas streams also require the efficient removal of these solids.The terminal settling velocity(Vts)of the solid particle is a vital parameter that controls the removal efficiency of these solids.In a drilling scenario when there is a hold on fluid cir-culation such as connection time,the accurate estimation of Vs provides the driller with time available to prevent solid deposition.In severe conditions,this can result in a stuck pipe,especially for extended-reach horizontal wells.In this work,both spherical and non-spherical particle deposition were experi-mentally investigated in several fluid rheology and salinity.Two concentrations(0.1 vol％and 0.05 vol％.)of partially-hydrolyzed polyacrylamide(PHPA)were used as a drag-reducing additive for water-based drilling mud.The PHPA drag-reducing fluid(reduced pressure loss)acts as a turbulence inhibitor.The PHPA polymer chain suppresses any turbulence in the flow,reducing the turbulent eddy viscosity.The effects of salinity(3 wt.％NaCl and 3 wt.％CaCl2 contamination)on solid particle settling velocity(Vs)in drag-reducing fluids were also investigated.Terminal velocity was achieved for all experiments and seemed to increase with increased diameter/sphericity.However,cases when this trend was not consistent were observed and therefore a new parameter of Φ(sphericity index x diameter)was pro-posed.Vs increases with Φ value for all cases.During drilling,PHPA also aids in sealing the fracture in the formation.With and without salt in the fluid,how lowering drag affected the settling velocity of solid particles(drill cuttings)could be observed.The settling velocity tests will be improved in drag-reducing PHPA solutions with the knowledge from this study.
Lei WangNurzhan YessenbayevXinchuang YanIliyas Sarmalayev...
359-368页
查看更多>>摘要：Karaganda Coal Basin bears the largest undeveloped reserve of coalbed methane(CBM)in Kazakhstan,which lacks water resources for implementing large-volume hydraulic fracturing.Cryogenic fracturing utilizing liquid nitrogen(LN2)has been trialled in fields and is a waterless fracturing technique under intensive research these days.This study aimed to evaluate the cryogenic treatment efficacy of Karaganda coal samples as well as to understand the coal permeability evolution during the thawing period.X-ray fluorescent spectrometry(XRF)and microscope imaging identified the compositional and structural heterogeneities of coal specimens mined from different interlayers.Acoustic emission test,permeability measurement,and microscope imaging comparatively characterized the dry coal structure alteration before and after immersion into LN2.Cryogenic treatment slowed down the S-wave velocity through coal specimens,enhanced permeability by over 65％after temperature recovery as well as created new fractures,enlarged existing ones,and spalled coal particles.Dynamic permeability evolution against temperature rise during the thawing process has been successfully captured for the first time.Overall,the experimental measurements support that the LN2 cryogenic fracturing technique would be effective in stimulating coalbeds for CBM production in Karaganda Coal Basin.
查看更多>>摘要：Production flow rates are crucial to make operational decisions,monitor,manage,and optimize oil and gas fields.Flow rates also have a financial importance to correctly allocate production to fiscal purposes required by regulatory agencies or to allocate production in fields owned by multiple operators.Despite its significance,usually only the total field production is measured in real time,which requires an alternative way to estimate wells'production.To address these challenges,this work presents a back allocation methodology that leverages real-time instrumentation,simulations,algorithms,and mathe-matical programming modeling to enhance well monitoring and assist in well test scheduling.The methodology comprises four modules:simulation,classification,error calculation,and optimization.These modules work together to characterize the flowline,wellbore,and reservoir,verify simulation outputs,minimize errors,and calculate flow rates while honoring the total platform flow rate.The well status generated through the classification module provides valuable information about the current condition of each well(i.e.if the well is deviating from the latest well test parameters),aiding in decision-making for well testing scheduling and prioritizing.The effectiveness of the methodology is demonstrated through its application to a representative offshore oil field with 14 producing wells and two years of daily production data.The results highlight the robustness of the methodology in properly classifying the wells and obtaining flow rates that honor the total platform flow rate.Furthermore,the methodology supports well test scheduling and provides reliable indicators for well conditions.By uti-lizing real-time data and advanced modeling techniques,this methodology enhances production monitoring and facilitates informed operational decision-making in the oil and gas industry.
查看更多>>摘要：This paper provides a comprehensive overview of Deep Transient Testing(DTT),a cutting-edge technique for reservoir characterization that has revolutionized the oil and gas industry.The main aim of DTT is to characterize the reservoir with a deeper radius of investigation.The optimization of the radius of investigation with the DTT approach is studied in detail.Reveal is a commercial numerical simulation application used to simulate the DTT process and evaluate the pressure wave analysis in the porous media.The main aim of the simulation is to understand the impact of the reservoir quality on the pressure response and use it to address the noise-to-pule ratio,which is a determinantal parameter in testing duration.The tested wells with the DTT tool show that measured well productivity can deliver the minimum commercial rate.The has been delivered within 2 days compared to the potential test time of 21 days which saved the 19 rig days and contributed to CO2 emission reduction of(gas flaring 1340+rig emission 600)1940 Metric tons equivalent to 421 cars emission in a year.However,DTT also presents certain limitations,such as the requirement for specialized equipment and expertise,as well as the potential for formation damage during testing.This study provides a detailed description of the DTT technique,encompassing its history,theory,and practical applications.Furthermore,it discusses the benefits and limitations of DTT and presents case studies to illustrate its effectiveness across various reservoir types.Overall,this study serves as a valuable resource for reservoir engineers,geologists,and other professionals involved in the exploration and production of oil and gas.
查看更多>>摘要：Parametric understanding for specifying formation characteristics can be perceived through conven-tional approaches.Significantly,attributes of reservoir lithology are practiced for hydrocarbon explora-tion.Well logging is conventional approach which is applicable to predict lithology efficiently as compared to geophysical modeling and petrophysical analysis due to cost effectiveness and suitable interpretation time.However,manual interpretation of lithology identification through well logging data requires domain expertise with an extended length of time for measurement.Therefore,in this study,Deep Neural Network(DNN)has been deployed to automate the lithology identification process from well logging data which would provide support by increasing time-effective for monitoring lithology.DNN model has been developed for predicting formation lithology leading to the optimization of the model through the thorough evaluation of the best parameters and hyperparameters including the number of neurons,number of layers,optimizer,learning rate,dropout values,and activation functions.Accuracy of the model is examined by utilizing different evaluation metrics through the division of the dataset into the subdomains of training,validation and testing.Additionally,an attempt is contributed to remove interception for formation lithology prediction while addressing the imbalanced nature of the associated dataset as well in the training process using class weight.It is assessed that accuracy is not a true and only reliable metric to evaluate the lithology classification model.The model with class weight recognizes all the classes but has low accuracy as well as a low F1-score while LSTM based model has high accuracy as well as a high F1-score.
查看更多>>摘要：Mantle plume is an essential component of the mantle convection system,and its influence on the geodynamics of continental rifts is of great significance for understanding the crust-mantle interaction.The East African Rift System,as the largest continental rift in the Cenozoic and in the initial stage,provides an excellent option for studying the interaction between the mantle plume and the continental crust.Based on the data such as GPS,seismic tomography,and global crustal model,a viscoelastic-plastic 2D thermodynamic numerical model is established to reconstruct the evolution of the Afar depression,Ethiopian Rift,and Kenyan Rift.By comparing the differences between the models of the Afar depression,Ethiopian Rift,and Kenyan Rift,the relationship between the mantle plume and pre-existing structures and their influence on the evolution of continental rifts are discussed.The results show that the mantle plume can increase the depth of the rift faults,concentrate the distribution of the faults,and strengthen the control of main faults on the rifts,allowing the possibility of narrow rifts.Pre-existing structures control the fault styles and symmetry of the rifts and also the morphology of the mantle plume.
查看更多>>摘要：Two independent barrier envelopes are the usual requirement used in most well operations to avoid catastrophic accidents.These are classified as primary-concerning preventing the occurrence of a kick,and secondary-concerning controlling the kick to avoid a blowout.Barrier envelopes consist of barrier elements,thus verifying the quality of these elements is fundamental.Barrier elements may be either redundant or mandatory,and these relationships are what constitute the barrier envelopes.In this work,we present a methodology to evaluate well safety by identifying existing barrier elements and barrier envelopes and mapping their relationships through the usage of graphs technique.This technique explicitly states the relationship between barriers and between them and envelopes.It enables a simpler visualization for well designers and allows the development of computer programs to control the safety and integrity of wells,both in the design phase and during drilling.12 graphs are provided for a 4-phase well(conductor,surface,production,and drill-in),considering both the primary and secondary enve-lopes.Reasoning for constructing each graph is thoroughly provided.If these graphs are used,reliability values can then be assigned to each barrier element,which results in the reliability of entire barrier envelopes.This can be further extended to analyze the safety of each operation by applying the system to operational sequences and even comparing well designs.
查看更多>>摘要：In this study,Hypermesh and LS-DYNA numerical simulation software are used to build a multi domain coupling model of natural gas pipeline,including soil,pipeline,TNT explosive and air domain,and the non-reflection boundary conditions are set for the model.The TNT equivalent method is used to convert the physical explosion amount of natural gas pipeline into 1387.38 kg TNT explosive amount.The simulation results show that the physical explosion of pipeline forms an approximate elliptical crater with a width of 12.68 m and a depth of 4.12 m;the TNT equivalent of the model is corrected by comparing the crater simulation value and the size value of the crater calculated by the PRCI empirical formula under the same laying condition,and the correction coefficient is selected as 0.9,and the cor-rected TNT equivalent is 1248.64 kg;the modified model crater size is 3.72 m deep and 12.66 m wide,compared with the crater size obtained from the field test,the error of crater depth and width calculated by the modified model simulation is 5.7％and 15.5％respectively.
查看更多>>摘要：The study delves into pore structure attributes within the complex Eocene carbonate of an Indian offshore field,encompassing pore throat,radius and their characteristics.Nuclear Magnetic Resonance(NMR)experimental data reveals crucial insights into pore structures and fluid states.This study com-pares the NMR T2 distribution curve with capillary pressure data from the Mercury Injection Capillary Pressure(MICP)technique,deriving linear and nonlinear conversion coefficients to transform NMR T2 spectra into equivalent pore radius distribution.Pore radius-dependent porosity partitioning,linked to permeability and the distribution of irreducible water,is conducted utilizing NMR-derived data.Following the T2 cut-off analysis,a two-segment fractal analysis of NMR T2 distribution is also carried out.This analysis unveils associations between fractal dimensions and various petrophysical parameters,including permeability,porosity,T2LM,irreducible water saturation and R50.The NMR-derived pore radius distribution is mostly unimodal,occasionally slightly bimodal.Six different pore size classes(less than 0.05 μm to more than 5 μm)are analysed in relation to permeability,porosity and irreducible water.Small pores(＜1 μm)contribute more to irreducible water with low porosity and permeability.The fractal dimension of large pores correlates strongly with porosity,permeability,T2LM,irreducible water and R50 suggesting significant impact on reservoir seepage capacity.In addition to porosity partitioning,the current study demonstrates effectiveness in modelling modified permeability and correlating it with in situ permeability when applied to field NMR log data from the study area.While numerous studies focus on sandstone,our study marks the pioneering attempt at a comprehensive analysis on complex car-bonate reservoirs.
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