The applicability and underlying factors of frequency-dependent amplitude-versus-offset(AVO)inversion

Recently,the great potential of seismic dispersion attributes in oil and gas exploration has attracted extensive attention.The frequency-dependent amplitude versus offset(FAVO)technology,with dispersion gradient as a hydrocarbon indicator,has developed rapidly.Based on the classical AVO theory,the technology works on the assumption that elastic parameters are frequency-dependent,and implements FAVO inversion using spectral decomposition methods,so that it can take dispersive effects into account and effectively overcome the limitations of the classical AVO.However,the factors that affect FAVO are complicated.To this end,we construct a unified equation for FAVO inversion by combining several Zoeppritz approximations.We study and compare two strategies respectively with(strategy 1)and without(strategy 2)velocity as inversion input data.Using theoretical models,we investigate the influence of various factors,such as the Zoeppritz approximation used,P-and S-wave velocity dispersion,inversion input data,the strong reflection caused by non-reservoir interfaces,and the noise level of the seismic data.Our results show that FAVO inversion based on different Zoeppritz approximations gives similar results.In addition,the inversion results of strategy 2 are generally equivalent to that of strategy 1,which means that strategy 2 can be used to obtain dispersion attributes even if the velocity is not available.We also found that the existence of non-reservoir strong reflection interface may cause significant false dispersion.Therefore,logging,geological,and other relevant data should be fully used to prevent this undesirable consequence.Both the P-and S-wave related dispersion obtained from FAVO can be used as good indicators of a hydrocarbon reservoir,but the P-wave dispersion is more reliable.In fact,due to the mutual coupling of P-and S-wave dispersion terms,the P-wave dispersion gradient inverted from PP reflection seismic data has a stronger hydrocarbon detection ability than the S-wave dispersion gradient.Moreover,there is little difference in using post-stack data or pre-stack angle gathers as inversion input when only the P-wave dispersion is desired.The real application examples further demonstrate that dispersion attributes can not only indicate the location of a hydrocarbon reservoir,but also,to a certain extent,reveal the physical properties of reservoirs.

Direct hydrocarbon identification in shale oil reservoirs using fluid dispersion attribute based on an extended frequency-dependent seismic inversion scheme

The identification of hydrocarbons using seismic methods is critical in the prediction of shale oil res-ervoirs.However,delineating shales of high oil saturation is challenging owing to the similarity in the elastic properties of oil-and water-bearing shales.The complexity of the organic matter properties associated with kerogen and hydrocarbon further complicates the characterization of shale oil reservoirs using seismic methods.Nevertheless,the inelastic shale properties associated with oil saturation can enable the utilization of velocity dispersion for hydrocarbon identification in shales.In this study,a seismic inversion scheme based on the fluid dispersion attribute was proposed for the estimation of hydrocarbon enrichment.In the proposed approach,the conventional frequency-dependent inversion scheme was extended by incorporating the PP-wave reflection coefficient presented in terms of the effective fluid bulk modulus.A rock physics model for shale oil reservoirs was constructed to describe the relationship between hydrocarbon saturation and shale inelasticity.According to the modeling results,the hydrocarbon sensitivity of the frequency-dependent effective fluid bulk modulus is superior to the traditional compressional wave velocity dispersion of shales.Quantitative analysis of the inversion re-sults based on synthetics also reveals that the proposed approach identifies the oil saturation and related hydrocarbon enrichment better than the above-mentioned conventional approach.Meanwhile,in real data applications,actual drilling results validate the superiority of the proposed fluid dispersion attribute as a useful hydrocarbon indicator in shale oil reservoirs.

Fluid discrimination incorporating viscoelasticity and frequency-dependent amplitude variation with offsets inversion

Frequency-dependent amplitude versus offset(FAVO)inversion is a popular method to estimate the frequency-dependent elastic parameters by using amplitude and frequency information of pre-stack seismic data to guide fluid identification.Current frequency-dependent AVO inversion methods are mainly based on elastic theory without the consideration of the viscoelasticity of oil/gas.A fluid discrimination approach is proposed in this study by incorporating the viscoelasticity and relevant FAVO inversion.Based on viscoelastic and rock physics theories,a frequency-dependent viscoelastic solid-liquid decoupling fluid factor is initially constructed,and its sensitivity in fluid discrimination is compared with other conventional fluid factors.Furthermore,a novel reflectivity equation is derived in terms of the viscoelastic solid-liquid decoupling fluid factor.Due to the introduction of viscoelastic theory,the proposed reflectivity is related to frequency,which is more widely applicable than the traditional elastic reflectivity equation directly derived from the elastic reflectivity equation on frequency.Finally,a pragmatic frequency-dependent inversion method is introduced to verify the feasibility of the equation for frequency-dependent viscoelastic solid-liquid decoupling fluid factor prediction.Synthetic and field data examples demonstrate the feasibility and stability of the proposed approach in fluid discrimination.

Fluid identification and effective fracture prediction based on frequency-dependent AVOAz inversion for fractured reservoirs

Fluid and effective fracture identification in reservoirs is a crucial part of reservoir prediction.The frequency-dependent AVO inversion algorithms have proven to be effective for identifying fluid through its dispersion property.However,the conventional frequency-dependent AVO inversion algorithms based on Smith&Gidlow and Aki&Richards approximations do not consider the acquisition azimuth of seismic data and neglect the effect of seismic anisotropic dispersion in the actual medium.The aligned fractures in the subsurface medium induce anisotropy.The seismic anisotropy should be considered while accounting for the seismic dispersion properties through fluid-saturated fractured reservoirs.Anisotropy in such reservoirs is frequency-related due to wave-induced fluid-flow(WIFF)between interconnected fractures and pores.It can be used to identify fluid and effective fractures(fluid-saturated)by using azimuthal seismic data via anisotropic dispersion properties.In this paper,based on Rüger’s equation,we derived an analytical expression in the frequency domain for the frequencydependent AVOAz inversion in terms of fracture orientation,dispersion gradient of isotropic background rock,anisotropic dispersion gradient,and the dispersion at a normal incident angle.The frequency-dependent AVOAz equation utilizes azimuthal seismic data and considers the effect of both isotropic and anisotropic dispersion.Reassigned Gabor Transform(RGT)is used to achieve highresolution frequency division data.We then propose the frequency-dependent AVOAz inversion method to identify fluid and characterize effective fractures in fractured porous reservoirs.Through application to high-qualified seismic data of dolomite and carbonate reservoirs,the results show that the method is useful for identifying fluid and effective fractures in fluid-saturated fractured rocks.

A high resolution inversion method for fluid factor with dynamic dryrock V_(P)/V_(S) ratio squared

As an important indicator parameter of fluid identification,fluid factor has always been a concern for scholars.However,when predicting Russell fluid factor or effective pore-fluid bulk modulus,it is necessary to introduce a new rock skeleton parameter which is the dry-rock VP/VS ratio squared(DVRS).In the process of fluid factor calculation or inversion,the existing methods take this parameter as a static constant,which has been estimated in advance,and then apply it to the fluid factor calculation and inversion.The fluid identification analysis based on a portion of the Marmousi 2 model and numerical forward modeling test show that,taking the DVRS as a static constant will limit the identification ability of fluid factor and reduce the inversion accuracy.To solve the above problems,we proposed a new method to regard the DVRS as a dynamic variable varying with depth and lithology for the first time,then apply it to fluid factor calculation and inversion.Firstly,the exact Zoeppritz equations are rewritten into a new form containing the fluid factor and DVRS of upper and lower layers.Next,the new equations are applied to the four parameters simultaneous inversion based on the generalized nonlinear inversion(GNI)method.The testing results on a portion of the Marmousi 2 model and field data show that dynamic DVRS can significantly improve the fluid factor identification ability,effectively suppress illusion.Both synthetic and filed data tests also demonstrate that the GNI method based on Bayesian deterministic inversion(BDI)theory can successfully solve the above four parameter simultaneous inversion problem,and taking the dynamic DVRS as a target inversion parameter can effectively improve the inversion accuracy of fluid factor.All these results completely verified the feasibility and effectiveness of the proposed method.

Amniotic fluid： Source of trophic factors for the developingintestine

The gastrointestinal tract(GIT) is a complex system, which changes in response to requirements of the body. GIT represents a barrier to the external environment. To achieve this, epithelial cells must renew rapidly. This renewal of epithelial cells starts in the fetal life under the influence of many GIT peptides by swallowing amniotic fluid(AF). Development and maturation of GIT is a very complex cascade that begins long before birth and continues during infancy and childhood by breastfeeding. Many factors like genetic preprogramming, local and systemic endocrine secretions and many trophic factors(TF) from swallowed AF contribute and modulate the development and growth of the GIT. GIT morphogenesis, differentiation and functional development depend on the activity of various TF in the AF. This manuscript will review the role of AF borne TF in the development of GIT.

Secretion of nerve growth factor,brain-derived neurotrophic factor,and glial cell-line derived neurotrophic factor in co-culture of four cell types in cerebrospinal fluid-containing medium

The present study co-cultured human embryonic olfactory ensheathJng cells, human Schwann cells, human amniotic epithelial cells and human vascular endothelial cells in complete culture medium- containing cerebrospinal fluid. Enzyme linked immunosorbent assay was used to detect nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor secretion in the supernatant of co-cultured cells. Results showed that the number of all cell types reached a peak at 7-10 days, and the expression of nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor peaked at 9 days. Levels of secreted nerve growth factor were four-fold higher than brain-derived neurotrophic factor, which was three-fold higher than glial cell line-derived neurotrophic factor. Increasing concentrations of cerebrospinal fluid （10%, 20% and 30%） in the growth medium caused a decrease of neurotrophic factor secretion Results indicated co-culture of human embryonic olfactory ensheathing cells, human Schwann cells human amniotic epithelial cells and human vascular endothelial cells improved the expression of nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor. The reduction of cerebrospinal fluid extravasation at the transplant site after spinal cord injury is beneficial for the survival and secretion of neurotrophic factors from transplanted cells.

Elevated Vascular Endothelia Growth Factor-A in the Serum and Peritoneal Fluid of Patients with Endometriosis

There has been emergence of evidence suggesting that specific variants of the vascular endothelia growth factor （VEGF） family, based on their ability to regulate angiogenesis, would be pivotal in the pathogenesis of endometriosis. This study was aimed at determining whether high levels of VEGF-A could be found in the serum and peritoneal fluid （PF） of patients with endometriosis. VEGF-A levels were measured by enzyme-linked immunosorbent assay （ELISA） in serum and PF from 46 patients with surgically confirmed endometriosis, and 40 controls with no clinical evidence of the disease or detectable endometriotic lesions at the time of surgical examination. The results showed the mean VEGF-A levels were significantly higher in the serum and PF of patients with endometriosis than in the controls. The VEGF-A levels in the serum and PF of patients with severe endometriosis （stages Ⅲ-Ⅳ） were significantly higher than in those with minimal endometriosis （P〈0.001）. It was concluded that endometriosis was associated with significant modulation in the levels of circulating VEGF-A.

Heat transfer and friction factor of Therminol liquid phase heat transfer fluid in a ribbed tube

Experiments and simulations on flow and heat transfer behavior of Therminol-55 liquid phase heat transfer fluid have been conducted in a ribbed tube with the outer diameter and inner diameter 25.0 and 20.0 mm,pitch and rib height of 4.5 and 1.0 mm.respectively.Experimental results show that the heat transfer and thermal performance of Therminol-55 liquid phase heat transfer fluid in the ribbed tube are considerably improved compared to those of the smooth tube.The Nusselt number increase with the increase of Reynolds number.The increase in heat transfer rate of the ribbed tube has a mean value of 2.24 times.Also,the pressure drop results reveal that the average friction factor of the ribbed tube is in a range of 2.4 and 2.8 times over the smooth tube.Numerical simulations of three-dimensional flow behavior of Therminol-55 liquid phase heat transfer fluid are carried out using three different turbulence models in the ribbed tube.The numerical results show that the heat transfer of ribbed tube is improved because vortices are generated behind ribs,which produce some disruptions to fluid flow and enhance heat transfer compared with smooth tube.The numerical results prove that the ribbed tube can improve heat transfer and fluid flow performances of Therminol liquid phase heat transfer fluid.

Changes of Nerve Growth Factor in Amniotic Fluid and Correlation with Ventriculomegaly

Objective To detect the change of nerve growth factor (NGF) level in human amniotic fluid during gestation, and to explore the relationship between this change and fetal ventriculo-megaly (VM). Methods The studied subjects (collected from 2004 to 2007) were divided into four groups, including the second-trimester pregnancy group (n=113), third-trimester pregnancy group (n=110), fetal cerebral VM group (n=12), and healthy control group (n=12) which matched with the VM group in gestational weeks. The amniotic fluid specimens were obtained during amniocentesis or cesarean section. The NGF levels in amniotic fluid were detected with en-zyme-linked immunosorbent assay. Results A significantly negative correlation was found between gestational age and the NGF level in amniotic fluid (r= 0.6149, P<0.0001). The NGF level in patients with fetal VM was significantly lower than that in healthy controls (33.95±29.24 pg/mL vs. 64.73±16.21 pg/mL, P=0.024). Conclusion NGF levels in amniotic fluid may be a sensitive marker for fetal VM.

Volumetric fluid analysis of fixed monthly anti-VEGF treatment in patients with neovascular age-related macular degeneration

·AIM:To evaluate visual outcomes and changes in fluid after administering monthly anti-vascular endothelial growth factor(VEGF)injections to treat neovascular agerelated macular degeneration(n AMD)with subretinal fluid(SRF)and pigment epithelial detachment(PED).·METHODS:This prospective study included eyes with n AMD previously treated with as-needed anti-VEGF injections.The patients were treated with six monthly intravitreal injections of ranibizumab.Quantitative volumetric segmentation analyses of the SRF and PED were performed.The main outcome measures included best-corrected visual acuity(BCVA),and SRF and PED volumes.·RESULTS:Twenty eyes of 20 patients were included in this study.At the 6-month follow-up,BCVA and PED volume did not change significantly(P=0.110 and 0.999,respectively)but the mean SRF volume decreased from 0.53±0.82 mm3 at baseline to 0.08±0.23 mm3(P=0.002).The absorption rate of the SRF volume was negatively correlated with the duration of previous antiVEGF treatment(P=0.029).Seven of the 20 eyes(35%)showed a fluid-free macula and significant improvement in BCVA(P=0.036)by month 6.·CONCLUSION:Quantifying the SRF can precisely determine the patient’s responsiveness to anti-VEGF treatment of n AMD.

Mechanism of Elevated Vascular Endothelial Growth Factor Levels in Peritoneal Fluids from Patients with Endometriosis

In order to investigate the mechanism of elevated vascular endothelial growth factor (VEGF) in peritoneal fluids from patients with endometriosis, macrophages were recovered from peritoneal fluids obtained at the time of diagnostic laparoscopy from infertile women with endometriosis (EMT group, n=20) and without endometriosis (control group, n=20). Macrophages were cultured in vitro. The VEGF levels of peritoneal fluid and the supernatant of macrophages culture were determined by enzyme linked immunoassay (ELISA). Meanwhile, the eutopic (n=20) and ectopic endometrium (n=20) from endometriosis patients, and normal edometrium (n=20) from non-endometriosis patients were obtained for the analysis of VEGF expression by labeled Streptavidin Biotin (LSAB). It was found that VEGF levels in peritoneal fluid and macrophages culture supernatant were significantly higher in EMT group than in control group (P<0.01). In normal endometrium, VEGF showed a cyclic changes and similar in eutopic and ectopic endometrium from patients with endometriosis. There was no difference in the intensity of VEGF in endometrium between two groups within each menstrual phase. It is suggested that altered VEGF production by peritoneal macrophages and ectopic endometrium secretion may contribute to the elevated VEGF levels in the peritoneal fluid of patients with endometriosis.

Relationship between endogenous digitalis－like factor and fluid therapy in burn－blast combined injury

Fifty dogs were inflicted with burn-blast combined injury and divided into 5 groups. All the experimental animals began to receive various amounts of fluid and sodium slat replacement 2 h after injury. Serum level of endogenous digitalis-like factor (EDLF

Effect of Third Interstitial Fluid on Adverse Outcomes in Patients with Severe Pre-eclampsia and Twin Pregnancy:A 5-year Single-center Retrospective Study

Objective This study aims to identify the effect of third interstitial fluid on adverse outcomes in twin pregnancies with severe pre-eclampsia,and explore the differences in bad ending between twins and singletons.Methods The present retrospective cohort study was conducted on patients with severe pre-eclampsia,who delivered in Tongji Hospital,Wuhan,China,between 2017 and 2022.The adverse outcomes in singleton and twin pregnancies with severe pre-eclampsia were initially investigated.Then,the diverse maternal and fetal consequences between singleton and twin pregnancies in patients with severe pre-eclampsia were compared after merging with the third interstitial fluid.Results A total of 709 patients were included for the present study.Among these patients,68 patients had twin pregnancies,and 641 patients had singleton pregnancies.The rate of postpartum hemorrhage(2.81%vs.13.24%,P<0.001),and admission rate to the Neonatal Intensive Care Unit(NICU)after birth(30.73%vs.63.24%,P=0.011)were significantly higher in twin pregnancies.The neonatal weight of twins was statistically lower than singletons(1964.73±510.61 g vs.2142.92±731.25 g,P=0.008).For the groups with the third interstitial fluid,the delivery week(P=0.001)and rate of admission to the NICU after birth were significantly advanced in twin pregnancy group,when compared to singleton pregnancy group(P=0.032),and the length of hospital stay was shorter(P=0.044).Furthermore,there was no statistically significant difference between the twin pregnancy group and the singletony pregnancy group without the third interstitial fluid.Conclusion The maternal and fetal adverse outcomes of patients with severe pre-eclampsia increased in twin pregnancies,when compared to singleton pregnancies.Thus,when patients develop the third interstitial fluid,twin pregnancies would more likely lead to adverse fetal outcomes,when compared to singleton pregnancies,and there would be no significant difference in maternal adverse outcomes.More attention should be given to patients who merge with the third interstitial fluid.

隧道突涌水灾害缩尺物理模型试验研究综述

随着我国经济的快速发展,隧道工程建设越来越多地面临着大埋深、高地应力、高地温、高渗透压力等复杂地质环境,运用物理模型试验开展复杂环境下隧道突涌水灾变机理与安全防控研究已成为岩石力学的热点问题。结合近年来国内外针对隧道突涌水灾变缩尺物理模型试验开展的研究工作,重点对该类物理模型的流固耦合相似理论、相似材料研制、渗透压加载方法等内容进行了系统梳理,并对下一步的可能发展方向进行展望。参考部分文献和突水典型案例后,总结了流固耦合相似准则和高地应力下的相似准则、相似材料选用方案及材料配比、试验中的水压加载方案,认为未来关注的重点包括考虑温度场的物理模型试验相似准则的研究和涌水涌泥与突水突泥间渐变过程的研究2个方面。

关节克痹丸联合西药治疗寒湿痹阻型膝骨关节炎临床研究

目的:观察关节克痹丸联合西药治疗膝骨关节炎(KOA)寒湿痹阻证的临床疗效。方法:选取90例KOA患者,按随机数字表法分为对照组及研究组各45例。对照组予以常规西药治疗,研究组在对照组基础上加用关节克痹丸治疗。比较2组临床疗效及不良反应发生率,比较2组治疗前后血清炎性因子[白细胞介素-6 (IL-6)、白细胞介素-1β (IL-1β)、肿瘤坏死因子-α (TNF-α)]、关节液Wntβ-catenin信号通路相关指标(Wnt-5a m RNA、β-catenin mRNA表达量)、中医证候积分、疼痛视觉模拟评分法(VAS)、美国特种外科医院(HSS)评分的变化。结果:研究组临床疗效总有效率为93.33%,对照组为77.78%,2组比较,差异有统计学意义(P<0.05)。治疗后,2组IL-6、IL-1β及TNF-α水平均较治疗前下降(P<0.05),研究组上述3项水平均低于对照组(P<0.05)。治疗后,2组Wnt-5a mRNA、β-catenin mRNA指标值均较治疗前下降(P<0.05),研究组上述2项指标值均低于对照组(P<0.05)。治疗后,2组中医证候积分及VAS评分均较治疗前下降(P<0.05),HSS评分均较治疗前上升(P<0.05);研究组中医证候积分及VAS评分均低于对照组(P<0.05),HSS评分高于对照组(P<0.05)。研究组不良反应发生率为6.67%,对照组不良反应发生率为11.11%,2组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:关节克痹丸联合西药治疗KOA能提升治疗有效率,改善临床症状,安全性高。

齿痛消炎灵颗粒联合甲硝唑对慢性根尖周炎患者根管治疗后炎症和疼痛的影响

目的:探讨齿痛消炎灵颗粒联合甲硝唑对慢性根尖周炎患者根管治疗后炎症和疼痛的影响。方法:选取2021年10月至2023年10月在该院行根管治疗的95例慢性根尖周炎患者进行前瞻性研究,按照随机数字表法将其分为对照组(n=47)和观察组(n=48)。在根管治疗基础上,对照组口服甲硝唑片治疗,观察组在对照组基础上联合齿痛消炎灵颗粒治疗。比较两组临床疗效,治疗前后牙周指标[牙龈指数(GI)、菌斑指数(PLI)]、龈沟液炎性因子[肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)]水平、视觉模拟评分法(VAS)评分,以及不良反应发生率。结果:观察组治疗总有效率为91.67%(44/48),高于对照组的76.60%(36/47),差异有统计学意义(P<0.05);治疗7 d后,观察组GI、PLI、VAS评分及龈沟液TNF-α、IL-1β、IL-6水平均低于对照组,差异有统计学意义(P<0.05);两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:齿痛消炎灵颗粒联合甲硝唑用于慢性根尖周炎根管治疗患者可提高临床疗效,改善牙周指标,降低龈沟液炎性因子水平,减轻牙齿疼痛,效果优于单用甲硝唑治疗。

不同熔附金属对前牙烤瓷熔附金属全冠修复疗效

目的对比研究镍铬合金与金沉积对前牙烤瓷熔附金属(porcelain-fused-to-metal crown,PFM)全冠修复患者的应用效果以及对龈沟液(gingival crevicular fluid,GCF)炎症因子的影响。方法选入2020年9月-2022年2月在本院接受前牙PFM全冠修复的患者86例(86颗牙),根据修复材料不同分为镍铬合金组和金沉积组,每组43例(43颗牙)。比较两组的治疗效果、GCF炎症因子水平等指标。结果金沉积组修复体颜色、边缘密合度、边缘着色及继发龋均显著优于镍铬合金组(P<0.05),在修复体折裂瓷崩方面,两组无明显差异(P>0.05);修复6个月后,金沉积组GI、PD、GCF和GCF中TNF-α、IL-6、IL-1β和MMP-2水平水平均显著低于镍铬合金组(P<0.05);金沉积组满意度显著高于镍铬合金组(93.02%vs.74.42%,P<0.05)。结论镍铬合金与金沉积均是前牙PFM全冠修复的常用材料,而后者对患者局部牙周组织影响较小,在减轻GCF炎性因子水平、提高修复美观度及患者满意度方面优于前者。

储层流体可动性在油田开发中的应用及展望

储层微观孔喉内流体可动性研究对于储层的精确评价和油藏的高效开发具有重要意义,是油气藏提高采收率的必要条件。依据研究对象的差异性,将孔喉流体可动性的研究方法分为矿物成分、孔隙结构及流体动用3个维度。核磁共振技术能够快速准确地确定可动流体饱和度、可动流体孔隙度和束缚水饱和度等常用的可动流体参数,进而有效地对各类油气储层进行流体评价和产能预测。目前,国内外各大油田均采用核磁共振与其他实验手段相结合的方法来确定储层内流体的动用规律,并在致密砂砾岩、碳酸盐岩、煤层和油页岩等不同类型储层中取得了良好的应用效果。另外,为了达到对不同类型油气资源的有效勘探和高效开发,必须明确储层内流体可动性的控制因素。在已有研究成果的基础上,流体可动性控制因素可以分为宏观和微观两方面,其中,宏观因素主要包括沉积环境、成岩作用和岩相类型;微观因素主要包括孔喉结构、储层物性、矿物成分及水膜厚度等。目前,虽然流体可动性研究方法的种类已较为丰富,并且在不同类型油气资源的评价中取得了良好的应用效果,但是,在其应用的广度和精度上还需要进一步深入研究与探索,在后续的发展中可综合应用孔隙网络模型、油藏数值模拟、多参数评价指标以及联立地球化学参数等新思路和新方法,深入揭示微观孔喉流体可动性的渗流机理,不断提高可动流体综合评价的精度,为油藏开发方案的合理制定提供地质依据,推动石油行业的高效发展。

钻井液侵入纹层状页岩的模型

井壁失稳一直是钻井工程中的世界性技术难题,纹层状页岩弱面发育以及黏土矿物含量较高,导致井眼坍塌的风险增加,极大地制约了页岩水平井的高效开发.为了研究钻井液在纹层状页岩中的侵入规律,开展了驱替实验和核磁扫描,确定了不同驱替时间下钻井液侵入纹层状页岩的深度,基于实验结果建立了新的包含纹层侵入的纹层状页岩的流体侵入数学模型,在总吸水量一定的情况下,可以根据侵入时间求得钻井液在纹层的侵入深度以及侵入量,基于实验结果验证了模型的准确性,采用有限元-离散元法描述钻井液侵入过程并进行敏感性分析.研究结果表明:在钻井液使用量一定的条件下,钻井液沿纹层状页岩油的侵入深度与侵入时间呈正向对数关系,随着侵入时间、纹层张开度的增大,侵入深度逐渐变大,但后期增长缓慢最终趋于不变;随着纹层数量的增加,侵入深度逐渐减小.