查看更多>>摘要：While computer modeling of annular displacement efficiency is widely applied in cementing engi-neering,modeling the displacement flow inside a casing or drill string for cementing operations has received less attention.Although predicting displacement efficiency inside a full-length pipe is desired by cementing engineers,the attempt of developing a model with both efficiency and accuracy faces challenges.Access to computer simulators for this purpose is limited.Compared with annular flow,the displacement flow inside pipe,although within a simpler geometry and without eccentricity effect,is not simpler in physics,modelling strategy and predictability,because a variety of flow patterns and flow instabilities can develop to create complicated fluid interfaces.In this paper,we present an integrated numerical model developed to simulate displacement flows inside a full-length pipe,which connects an existing annulus model to enable complete displacement simulations of cementing jobs.The model uses three-dimensional grid to solve fluid concentrations with degrees of mixing,and incorporates flow instability detection and flow regime determination.Applied in cementing,the model accounts for ef-fects of pumping rate,well inclination,pipe rotation,fluid densities,rheological parameters and more.This computationally efficient model does not rely on high-resolution mesh as often required by con-ventional Computational Fluid Dynamics models,thus it is suitable to be implemented in a cementing software for daily use by well cementing engineers.The methodology of the model is discussed in detail in this paper.To validate the model,we examine simulation results against experimental results obtained in our laboratory tests and CFD simulations;acceptable agreement is found under different testing conditions.We also presented two case studies of real cementing jobs with cement evaluation logs compared to simulation results,showing that the model can predict consistent displacement efficiency results.
Erfan HosseiniDana Mohammad NazarNegar HosseiniMohammad Sarmadivaleh...
17-36页
查看更多>>摘要：Water flooding and pressure maintenance are recommended to improve oil recovery practices after low recovery of petroleum reservoirs occurs during primary production.Salt crystal formation is a frequent occurrence when using these techniques.Several experimental,numerical,and theoretical studies have been done on the mechanisms underlying scaling and permeability reduction in porous media;however,there has not been a satisfactory model developed.This study developed a phenomenological model to predict formation damage caused by salt deposition.Compared with existing models,which provide a scaling tendency,the proposed model predicts the profile of scale deposition.The salt precipitation model simulates reactive fluid flow through porous media.A thermodynamic,kinetic,and flow hydro-dynamic model was developed and coupled with the ion transport equation to describe the movement of ions.Further,a set of carefully designed dynamic experiments were conducted and the data were compared with the model predictions.Model forecasts and experimental data were observed to have an average absolute error(AAE)ranging from 0.68％to 5.94％,which indicates the model's suitability.
查看更多>>摘要：Lucaogou Formation in the Santanghu Basin is a special lacustrine fine-grained sedimentary deposits rich in volcanic debris and carbonate,with abundant shale oil resources.However,understanding of shale oil characteristics and genesis remains unclear.Lithofacies,sedimentary environment,and formation mechanisms of tuffaceous shale oil are investigated based on core and thin section observations,X-ray diffraction,field emission SEM and geochemical analysis.Results show that three mixed lithofacies types are developed in Lucaogou Formation:blocky tuff,laminated tuffaceous dolomite,and laminated dolomitic tuff.These lithofacies types are characterized by high content of felsic and dolostone,wide-spread organic matter,and low clay content.Formation of tuffaceous shale oil sweet spots is primarily influenced by four factors:inputting of volcanic ash as a high-quality source rocks and reservoirs pro-vides good material basis;devitrification of volcanic glass,calcitization,and dissolution are crucial for formation of reservoirs;expulsion of source rocks with high-abundance organic matter expulsion fa-cilitates migration and accumulation of hydrocarbon in adjacent reservoirs;fracture development im-proves reservoir permeability to form highly productive sweet spots.By analyzing characteristics and genesis of tuffaceous shale oil,the main controlling factors of reservoir physical property and oil satu-ration are clarified,which is of great significance for selection of shale oil exploration zones.
查看更多>>摘要：This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering technique.The ob-jects of the study were four samples of asphaltenes obtained from four different oils.For all samples,the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant(heptane)to a solution of asphaltenes in toluene at an amount above the threshold concentration.Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment,which led to the destruction of the asphaltene aggregates.Aggregation of destroyed asphaltenes was observed.The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant.Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation:the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.
查看更多>>摘要：Foam flooding using CO2 has emerged as a promising method for both enhanced oil recovery(EOR)and the storage of CO2 in geological reservoirs.This study conducts a thorough analysis of the behavior of CO2 and N2 foams in bulk and porous media,utilizing bubble-scale analyses and foam flooding experiments.The study compares the foamability and longevity of CO2 and N2 foams,with findings indicating that N2 foam bubbles tend to be smaller and less varied in size than CO2 foam bubbles,leading to increased foam stability.Additionally,the study compares the half-lives of CO2 and N2 foams generated through sparging and winding methods,showing that N2 foam has half-lives 22 and 10 times greater than CO2 foam when produced using the sparging and winding methods,respectively.Furthermore,CO2 foam generated through the sparging method had a lower foaming volume than N2 foam due to CO2's solubility.In the foam flooding experiments,N2 foam proved more effective in recovering oil from porous media than CO2 foam,thus demonstrating the effectiveness of the foam injection procedure.These results offer valuable insights into the differing performance of N2 and CO2 foam floods for EOR and CO2 geological storage.
查看更多>>摘要：The Mishrif Formation(Cenomanian-E Turonian)is one of the most important geological formations in the Middle East and Iraq because it contains enormous petroleum accumulations.It is considered to be the first reservoir in the region,and is still being studied because of its economic significance.The carbonate of the Mishrif Formation derives from a variety of depositional settings,including mid-ramp,shoal,lagoon,and intertidal.The five main microfacies discussed in this paper are wackestone,pack-stone,grainstone,floatstone,and bindstone.The most frequent fossilised components found in the Mishrif Formation are rudists,benthic foraminifera,echinoderms,burrows molluscs,and algae.Ac-cording to the microfacies and analysed wireline log data,the sequence stratigraphy of the studied formation is composed of two regression cycles.Five parasequences of transgressive-regressive cycles make up the depositional sequence of the Mishrif Formation.The standard depositional environments seem to demonstrate a gradual regression,beginning with a short period of the outer ramp,then a steady period of the mid-ramp,and ending in the intertidal environment.Additionally,the study recorded two regional maximum flooding surfaces:K-135 and K-140.The former is present in the lowermost part of the formation,while the other lies in the middle.This study shows a close relationship between facies(environments)and hydrocarbon accumulation.The increased accumulation focuses on the lower part of the studied formation,and seems to be lower in the upper part of the formation as a result of changes in the environment of deposition.
查看更多>>摘要：During the life of a well,treatments are carried out to boost productivity by stimulating initially un-produced zones.These treatments include hydraulic fracturing,matrix acidization,and acid fracturing,among others.Hydraulic fracturing treatment is generally applied to deeper reservoirs of oil or natural gas for enhanced recovery.By infusing proppant,water,and chemicals under extreme pressure during the fracturing procedure,fissures in and beneath the reservoir layer can be accessed and expanded.Another stimulating procedure,matrix acidization,involves injecting acid down the drilling hole to permeate the rock fissures at stresses lower than the fracture stress.In addition,carbonate reservoir acid fracturing stimulation is commonly used as an acid treatment technique whereby a pressure greater than the formation disintegration pressure or spontaneous fracture closure pressure is used to compress acid into the reservoir.These treatments allow existing wells to sustain hydrocarbon production without new wells being drilled.Diverters,when employed efficiently,can prevent the need to use a rig to provide momentary physical barriers,thus lowering the cost of the workover.Recent improvements in diversion technology make use of a variety of degradable particles that act as momentary bridges,either at the perforation entries or inside the existing fractures.The aim of this study is to introduce different types of mechanical and chemical diverters used to enhance the productivity of wells.This study explains the concepts of different types of diverters and their applications in several formations,it will also help readers to understand the selection procedures based on the suitability and requirements of diverter use by case studies from around the world.
查看更多>>摘要：The asphaltene fractions of the bitumens of Eastern Dahomey Basin in Nigeria,were analyzed by flash pyrolysis-gas chromatography(Py-GC)method in order to unravel its geochemical history and proper-ties.The distributions of the initial biomarkers of the original oils from the pyrolysates are related to the assessment of organic matter source,paleo-redox conditions and source environment during deposition.Also,it effectively establishes the genetic relationship of the bitumens.The n-alkane distributions in the pyrolysates reveal nC9-nC32 n-alkanes,maximizing at nC14,isoprenoids-pristane(Pr)and phytane(Ph),and some n-alkene peaks.High peaks of low to medium-weight nC9-nC20 n-alkanes and low peaks of nC21+n-alkanes characterize the distributions.These reveal that abundant algal organic matter with some terrigenous inputs contributed to the source rock of the bitumens.The high concentration of marine organic matter inputs to the source rock is further confirmed by the nC17/nC27 ratios which range from 5.39 to 19.82 and shows the predominance of nC17 alkanes.The general unimodal n-alkane dis-tributions in the bitumens indicate derivation from similar organic matter types showing that they are genetically related.The anoxic to suboxic environmental conditions that prevailed during the deposition of the sediments is revealed by the isoprenoids,Pr/Ph ratios(0.72-1.28).Pristane/nC17 and Phytane/nC18 range from 0.16 to 0.33 and 0.22 to 0.56,revealing that the bitumens were from predominantly marine organic matter(type Ⅱ kerogen)preserved in a reducing environment with no evidence of biodegra-dation.However,the Ph/nC18 ratio and the cross plot of Pr+Ph/nC17+nC18 allow the classification of the bitumens into two subfamilies/groups(A and B).The bitumen samples have low wax content as indi-cated by the degree of waxiness ranging from 0.21 to 0.38 which confirms low terrigenous input.Based on the carbon preference index(CPI:0.92 to 1.55)and odd-even predominance(OEP:0.70 to 1.36),it is concluded that the bitumens are immature to marginally mature.
查看更多>>摘要：In this study,the employment of mud-pulse generators to improve the efficiency of wellbores under complex mining and geological conditions is examined.A systemic analysis is made of the primary theoretical basis of the study.The benefits of a mud-pulse generator(a high-impulse hydraulic hammer)for wellbore production are stated based on the presented theoretical basis.The results not only show the benefits of mud-pulse generator employment but also provide an analysis of methods that can be used to improve the high-impulse hydraulic hammer efficiency.The acquired results have a substantial practical value not only for specialists,who research,develop,and manage wellbore operations,but also for engineers,who improve the process and modernize existing wellbores,and other experts in the field of wellbore production.
查看更多>>摘要：Conformance control or water shut-off is a technique used to improve oil recovery.During conformance control,polymers block high permeability water areas and redistribute water drive toward unswept oil zones.In this study,co-polymers(denoted ATP-PGV/AM-co-AMPS)were synthesized using acrylamide(AM)and 2-acrylamide-2-methylpropane sulfonic acid(AMPS)as the monomers,polyethylene glycol(PEG)-200 and methylenebisacrylamide(MBA)as the crosslinkers,attapulgite(ATP)and bentonite(PGV)as the clay types,and ammonium persulfate(APS)as the initiator,in addition to paraffin oil and sur-factants.Samples were synthesized using inverse emulsion polymerization with different concentrations of monomers,crosslinkers,and clays,and they were characterized using Fourier-transform infrared(FTIR)spectroscopy and scanning electron microscopy(SEM)with energy dispersive X-ray spectroscopy(EDX).FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups,which are important for polymer swelling.SEM-EDX images indicated that the morphology and elemental composition were different before and after swelling,confirming the occurrence of swelling.Moreover,samples were placed in sodium chloride solution(20,000 ppm)for 7 days to evaluate swelling at both room temperature and 90 ℃.Thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)were used to determine the thermal characteristics of the microparticles.Finally,rheological measurements were used to assess the deformation and rheological behavior of the hydrogels.The re-sults showed that after 1 day,good swelling without loss of mechanical strength was achieved with the composite synthesized using 10％AM,15％AMPS,6％PGV,and 10％ATP.
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