Effect of fracture fluid flowback on shale microfractures using CT scanning

The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.

Does progress in microfracture techniques necessarily translate into clinical effectiveness?

BACKGROUND Multitudinous advancements have been made to the traditional microfracture(MFx)technique,which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of cartilage defect.The relative benefits and pitfalls of these diverse modifications of MFx technique are still not widely understood.AIM To comparatively analyze the functional,radiological,and histological outcomes,and complications of various generations of MFx available for the treatment of cartilage defects.METHODS A systematic review was performed using PubMed,EMBASE,Web of Science,Cochrane,and Scopus.Patients of any age and sex with cartilage defects undergoing any form of MFx were considered for analysis.We included only randomized controlled trials(RCTs)reporting functional,radiological,histological outcomes or complications of various generations of MFx for the management of cartilage defects.Network meta-analysis(NMA)was conducted in Stata and Cochrane’s Confidence in NMA approach was utilized for appraisal of evidence.RESULTS Forty-four RCTs were included in the analysis with patients of mean age of 39.40(±9.46)years.Upon comparing the results of the other generations with MFX-I as a constant comparator,we noted a trend towards better pain control and functional outcome(KOOS,IKDC,and Cincinnati scores)at the end of 1-,2-,and 5-year time points with MFx-III,although the differences were not statistically significant(P>0.05).We also noted statistically significant Magnetic resonance observation of cartilage repair tissue score in the higher generations of microfracture(weighted mean difference:17.44,95%confidence interval:0.72,34.16,P=0.025;without significant heterogeneity)at 1 year.However,the difference was not maintained at 2 years.There was a trend towards better defect filling on MRI with the second and third generation MFx,although the difference was not statistically significant(P>0.05).CONCLUSION The higher generations of traditional MFx technique utilizing acellular and cellular components to augment its potential in the management of cartilage defects has shown only marginal improvement in the clinical and radiological outcomes.

Enhanced microfracture techniques in cartilage knee surgery: Fact or fiction?

The limited intrinsic healing potential of human articular cartilage is a well-known problem in orthopedic surgery. Thus a variety of surgical techniques have been developed to reduce joint pain, improve joint function and delay the onset of osteoarthritis. Microfractures as a bone marrow stimulation technique present the most common applied articular cartilage repair procedure today. Unfortunately the deficiencies of fibrocartilaginous repair tissue inevitably lead to breakdown under normal joint loading and clinical results deteriorate with time. To overcome the shortcomings of microfracture, an enhanced microfracture technique was developed with an additional collagen Ⅰ/Ⅲ membrane(Autologous, Matrix-Induced Chondrogenesis, AMIC). This article reviews the pre-clinical rationale of microfractures and AMIC, presents clinical studies and shows the advantages and disadvantages of these widely usedtechniques. PubM ed and the Cochrane database were searched to identify relevant studies. We used a comprehensive search strategy with no date or language restrictions to locate studies that examined the AMIC technique and microfracture. Search keywords included cartilage, microfracture, AMIC, knee, ChondroGide. Besides this, we included our own experiences and study authors were contacted if more and non published data were needed. Both cartilage repair techniques represent an effective and safe method of treating full-thickness chondral defects of the knee in selected cases. While results after microfracture deteriorate with time, mid-term results after AMIC seem to be enduring. Randomized studies with long-term followup are needed whether the grafted area will maintain functional improvement and structural integrity over time.

DEFORMATION AND MICROFRACTURE OF GRANULAR BAINITE

Relationship among deformation history,fracture process and stress distribution of granular bainite has been investigated.The main process of fracture of granular bainite is the forma- tion.growth and coalescence of the microvoids.Even though the microcracks have formed at the earlier stage of deformation,they are not fateful for fracture because in the successive deformation stage the microcracks change their orientation toward the tensile axis.The strain hardening rate of granular bainite has a minimal value during the deformation process. Before and after the strain of the minimal value,the material shows different stress distribu- tion and microfracture mechanism.

Identification and characterization of microfractures in carbonate samples

Based on the rock typing method of pore geometry and structure(PGS), rock samples from carbonate reservoir A and carbonate reservoir B were classified using data of routine and special core analysis and thin section images, and microfractures in the carbonate reservoir samples were identified and characterized. Establishment of rock types demonstrates that microfractures have developed in all rock types in carbonate reservoir A, but only partially in certain rock types in carbonate reservoir B with porosity of 1%–11%, less vuggy, and hardness of medium hard to hard. The cut-off porosity was determined for each type of rock to distinguish samples with and without conductive microfractures. The impact of conductive microfractures on improving permeability was analyzed. On the basis of relationship of permeability and original initial water saturation, the permeability equation was derived by certain special core analysis data with conductive microfractures selected by PGS equation, and the permeability of samples with conductive microfractures has been successfully predicted.

Stability analysis of surrounding rock mass in underground powerhouse considering damage effect of microfractures

A high-precision microseismic(MS)monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station.The surrounding rock damage area with spatiotemporal clustering of MS activities was studied for qualitative analysis of the damage mechanism of surrounding rock microfractures,based on the source parameters of MS events.The surrounding rock microfracture scale characterized by the source radius of MS events was considered to establish the constitutive relation.MS information was imported into the model for numerical analysis using fast Lagrangian analysis of continuain 3 dimensions(FLAC^(3D)).The results indicated that the numerical simulation results considering MS damage can better reflect the actual situation of the field.The surrounding rock microfractures mainly showed mixed failure characteristics.Shear failures appeared in localized areas while the fracture scale of sections from K0e33 m to K0e15 m on the vault was large.The deformation increment caused by microfracture damage in the shallow surrounding rock of the top arch accounted for 10%e13%,and the stress decrement in the surrounding rock caused by microfracture damage accounted for about 10%.

Repair of articular cartilage defects in minipigs by microfracture surgery and BMSCs transplantation

Objective:To investigate the feasibility of minimal invasive repair of cartilage defect by arthroscope-aided microfracture surgery and autologous transplantation of mesenchymal stem cells. Methods: Bone marrow of minipigs was taken out and the bone marrow derived mesenchymal stem cells (BMSCs) were isolated and cultured to passage 3. Then 6 minipigs were randomly divided into 2 groups with 6 knees in each group. After the articular cartilage defect was induced in each knee, the left defect received microfracture surgery and was injected with 2.5 ml BMSCs cells at a concentration of 3×107 cells/ml into the articular cavity; while right knee got single microfracture or served as blank control group. The animals were killed at 8 or 16 weeks, and the repair tissue was histologically and immunohistochemically examined for the presence of type Ⅱ collagen and glycosaminoglycans (GAGs) at 8 and 16 weeks. Results: Eight weeks after the surgery, the overlying articular surface of the cartilage defect showed normal color and integrated to adjacent cartilage. And 16 weeks after surgery, hyaline cartilage was observed at the repairing tissues and immunostaining indicated the diffuse presence of this type Ⅱ collagen and GAGs throughout the repair cartilage in the treated defects. Single microfracture group had the repairing of fibrocartilage, while during the treatment, the defects of blank group were covered with fewer fiber tissues, and no blood capillary growth or any immunological rejection was observed. Conclusion: Microfracture technique and BMSCs transplantation to repair cartilage defect is characterized with minimal invasion and easy operation, and it will greatly promote the regeneration repair of articular cartilage defect.

Quantitative characterization of irregular microfracture network and its effect on the permeability of porous media

Based on the comprehensive understanding on microfractures and matrix pores in reservoir rocks,numerical algorithms are used to construct fractured porous media and fracture-pore media models.Connectivity coefficient and strike factor are introduced into the models to quantitatively characterize the connectivity and strike of fracture network,respectively.The influences of fracture aperture,fracture strike and fracture connectivity on the permeability of porous media are studied by using multi-relaxation-time lattice Boltzmann model to simulate fluid flow in them.The greater the strike factor and the smaller the tortuosity of the fractured porous media,the greater the permeability of the fractured porous media.The greater the connectivity coefficient of the fracture network is,the greater the permeability of the fracture-pore media is,and the more likely dominant channel effect occurs.The fracture network connectivity has stronger influence on seepage ability of fracture-pore media than fracture aperture and fracture strike.The tortuosity and strike factor of fracture network in fractured porous media are in polynomial relation,while the permeability and fracture network connectivity coefficient of the fracture-pore media meet an exponential relation.

Effects of Early Weightbearing on Microfracture Treatment of Osteochondral Lesions of Talus with Subchondral Bone Defects

When subchondral bone defects are present in osteochondral lesions of the talus(OCLT),it is inconclusive whether to allow early weightbearing after microfracture treatment because of the lack of effective support of the newly-formed fibrocartilage.After performing arthroscopic debridement and microfracture treatment on OCLT patients with subchondral bone defects,we allowed patients to have an early postoperative weightbearing exercise to observe their clinical outcome.Forty-two OCLT patients with subchondral bone defects were analyzed.Patients were randomly divided into two groups with 21 patients in each group.After arthroscopic debridement and microfracture treatment,group A was allowed to have early partial weightbearing while weightbearing was delayed in group B.Visual analogue scale(VAS)was used to evaluate joint pain before and after surgery.American Orthopaedic Foot and Ankle Society(AOFAS)anklc-hindfoot score was used to evaluate joint function.Tegner activity scale was used to assess patient's exercise level.The AOFAS ankle-hindfoot score in group A increased from 54.4 to 87.6,and that in group B increased from 54.9 to 87.3.The VAS score in group A decreased from 6.5 to 2.2,and that in group B decreased from 6.4 to 2.3.The Tegner activity scale increased from 2.6 to 4.4 in group A,and that in group B increased from 2.6 to 3.9.There was significant difference in the Tegner activity scale between group A and group B(P<0.05).It was suggested that when performing microfracture treatmenf on OCLT patients with subchondral bone defects,early postoperative weightbearing may achieve similar clinical outcomes as delayed weightbearing,and patients may be better able to return to sports.

Imaging dynamic water invasion behavior in microfractures based on microfluidics

Fluid invasion through fractures is frequently observed in subsurface engineering. To elucidate the microkinetic behavior of fracture fluids, the microfracture structure of coal from the Surat Basin was reconstructed using a 3D morphometric system and stitching algorithm, then the transparent models characterizing the fracture structure were produced using microfluidics, and water invasion in the microfracture model was measured via visualization experiments under various conditions. High flow rate facilitated the invasion of the water phase into the closed channel, improving the efficiency of water invasion in the neutral wetting system. Wettability reversal changed the dominant channel for water invasion in the hydrophobic system. The invasion efficiency in closed and small aperture bypass channels was low.The reduction of effective seepage channels led to the fastest breakthrough time. Higher surface tension and interfacial curvature promoted the hysteresis effect. The reduction of effective seepage channels led to the fastest breakthrough time. The larger surface tension and interfacial curvature make the hysteresis effect more significant. These results will enable a better understanding of the rock-gas-liquid multiphase interaction mechanisms under unsaturated conditions of rocks.

Early Weight Bearing Post Subchondral Microfracture Knee Arthroscopy: A Case Report

Traditionally physicians have advised patients to be non-weight bearing post arthroscopic knee microfracture surgery for at least 2 to 8 weeks. The microfracture procedure is a simple, low-risk method to induce self-cartilage regeneration to focal lesions. The procedure has shown that small fractures to the subchondral bone can recruit mesenchymal stem cells and growth factors to regenerate the fibrocartilage without compromising the subchondral plate. With the simplicity of this procedure and the positive effect it can have on patients, it is natural to want to push the bounds of rehabilitation to see what is necessary. The patient in this case report exhibits the potential for positive outcomes with early weight-bearing status in patients receiving microfractures via subchondral drilling. This positive outcome, along with others, should encourage clinicians to consider reestablishing evidence-guided rehabilitation post microfracture with new studies. Shortened rehabilitation time would decrease a barrier to surgery for many patients and would only enhance our treatment with this surgical modality.

接骨丹联合关节镜下微骨折术治疗膝骨性关节炎的临床疗效观察

目的观察接骨丹联合关节镜下微骨折术治疗膝骨性关节炎(KOA)的临床疗效。方法纳入2019年1月至2023年6月漳州市中医院骨科共计60例KOA患者,分组方法:随机数字表法,分为30例对照组和30例试验组。对照组采用关节镜下微骨折术治疗KOA,试验组术后在对照组基础上加用接骨丹治疗。手术前、术后1个月、术后6个月,比较两组患者VAS评分、Lysholm评分、HSS评分情况。结果两组VAS评分、Lysholm评分、HSS评分治疗前比较无统计学意义(P>0.05);治疗后,两组各项评分均优于治疗前,且试验组优于对照组(P<0.05)。结论接骨丹联合关节镜下微骨折术治疗KOA临床疗效显著,可有效减轻疼痛、促进膝关节功能恢复。

距骨骨软骨损伤治疗方案的个性化组合

背景:距骨骨软骨损伤根据不同分型或临床症状,采取不同的治疗方法,包括保守治疗、手术治疗和生物制剂治疗。保守治疗大多可短时缓解症状和延缓病情;近年来关节镜下微骨折、克氏针钻孔、距骨软骨移植、自体骨软骨细胞移植、干细胞移植和生物制剂富血小板血浆等方法,都取得了不错的疗效。目的:对距骨骨软骨损伤的治疗进展进行总结,为其临床治疗提供参考。方法:第一作者以“talus,osteochondral lesions of the talus,微骨折,移植术,富血小板血浆,干细胞”为检索词,检索Pub Med数据库及中国知网2019年1月至2024年1月的相关文章。共纳入67篇文献进行综合分析。结果与结论:(1)目前治疗距骨骨软骨损伤的方式较多,对于Hepple分型Ⅰ和Ⅱ型病变保守康复治疗和生物制剂可缓解病情;Hepple分型Ⅲ型及以上且病变直径<15 mm选择微骨折或克氏针钻孔骨髓刺激治疗,但长期疗效不佳;更大病变面积选择置换和再生策略,移植失败是其最主要风险;(2)生物制剂治疗作为一种治疗新方式,多用于组合治疗;(3)针对距骨骨软骨损伤的治疗,需要考虑到软骨损伤的面积、部位等诸多因素,其治疗方案的选择还应考虑医疗技术开展情况以及患者接受程度、经济状况等因素,建议对各种方案进行个性化组合治疗,以取得更为良好的效果。

Arthroscopic patellar denervation with microfracture for treating patellofemoral arthritis in cold weather conditions:a retrospective clinical analysis

Objective:To evaluate the clinical efficacy of combining arthroscopic patellar denervation with microfracture in the treatment of patellofemoral arthritis under cold weather conditions.Methods:A total of 134 patients with patellofemoral arthritis who underwent treatment between June 2019 and June 2021 were included in this study.Patients were randomly divided into two groups:the control group,which received standard arthroscopic debridement and conventional therapy,and the study group,which underwent additional peripatellar denervation and microfracture procedures.Clinical outcomes,including Tegner scores,hospital for special surgery(HSS)scores,and treatment-related adverse events,were evaluated and compared between the two groups.Results:The study group achieved a significantly higher excellent treatment rate(95.52%,64/67)compared to the control group.Post-treatment Tegner scores(5.48±1.86)and HSS scores(86.37±11.25)were also significantly better in the study group than in the control group.Furthermore,the incidence of adverse reactions was lower in the study group(4.48%,3/67),with statistically significant differences observed(P<0.05).Conclusions:Arthroscopic patellar denervation combined with microfracture markedly improves clinical outcomes,including Tegner and HSS scores,in the treatment of patellofemoral arthritis,particularly under cold weather conditions.The procedure is effective and safe,supporting its broader clinical application.

创伤性膝关节骨性关节炎患者行关节镜微骨折术效果及术后下肢静脉血栓形成危险因素分析

目的 分析创伤性膝关节骨性关节炎(TKOA)患者行关节镜微骨折术效果及术后下肢静脉血栓形成危险因素。方法 回顾性选取2020年3月至2023年3月佳木斯市中心医院收治的80例TKOA患者进行研究,按照治疗方法不同将其分为对照组(n=30)与观察组(n=50)。对照组行常规膝关节手术,观察组行关节镜微骨折术,分析两组的临床治疗效果和下肢静脉血栓发生率。另根据术后是否发生下肢静脉血栓将观察组患者分为有血栓组和无血栓组,分析两组患者的一般特征,并建立多因素Logistic模型分析分析影响关节镜微骨折术后下肢静脉血栓形成的独立危险因素。结果 观察组的总有效率为96.00%,高于对照组(80.00%),差异有统计学意义(P<0.05)。观察组下肢静脉血栓发生率为24.00%,低于对照组(46.67%),差异有统计学意义(P<0.05)。与无血栓组比较,有血栓组年龄≥60岁、高血脂症、止血带应用时间>90 min、术后卧床时间≥3 d、手术时间≥1 h率和Caprini评分较高(P<0.05)。单因素分析结果显示,年龄、高血脂症、止血带应用时间、术后卧床时间、手术时间、Caprini评分均是TKOA患者关节镜微骨折术后下肢静脉血栓形成的影响因素(P<0.05)。多因素Logistic分析结果显示,年龄≥60岁、高血脂症、止血带应用时间>90 min、术后卧床时间≥3 d、手术时间≥1 h、Caprini评分均是TKOA患者关节镜微骨折术后下肢静脉血栓形成的独立危险因素(P<0.05)。结论 关节镜微骨折术在TKOA治疗中效果较为显著,但受年龄过大、术后卧床时间和手术时间过长等因素影响极易引发下肢静脉血栓,只有加强对该类影响因素的预防干预,才能有效降低患儿的下肢静脉血栓形成风险。

MRI术前定量评估距骨骨软骨损伤范围对术式选择及中长期随访结果的影响

背景:距骨骨软骨损伤是一种常见的运动系统疾病,该损伤类型会影响患者的日常生活和工作能力,如不及时治疗可能加重病情。手术治疗是常用的治疗方法,但术式选择和中长期随访结果的评估一直是临床上的难题。目的:探究术前T1ρ技术定量评估距骨骨软骨损伤范围对术式选择及中长期随访结果的影响。方法:回顾性选择2019年1月至2022年8月唐山市第二医院收治的距骨骨软骨损伤患者154例作为研究对象。术前MRI检查距骨骨软骨损伤部位,比较不同分型患者的T1ρ值及T2值;再根据T1ρ值选择不同的手术方式,将T1ρ值<45 ms采用微骨折手术治疗设为A组(n=73),T1ρ值≥45 ms采用自体骨软骨移植治疗设为B组(n=81)。比较不同术式下患者的一般临床特征及疗效,多因素Logistic回归分析患者术后复发的重要因素,限制性立方样条图分析T1ρ值与患者术后复发的关系,y=1-1/(1+e-z)回归方程建立预测模型,十字交叉验证法验证模型稳定性。结果与结论:①154例患者中距骨骨软骨损伤分型Ⅰ型36例,Ⅱ型37例,Ⅲ型40例,Ⅳ型41例,4个分型患者的T1ρ值及T2值相比差异均有显著性意义(P<0.05),两两比较差异亦有显著性意义(P均<0.05);②154例患者治疗后局部肿胀7例(4.6%),疼痛加重3例(2.0%),创口感染5例(3.3%),软骨愈合不良2例(1.3%);③A、B组治疗后美国骨科足踝协会评分、目测类比评分、跖屈活动度、背伸活动度、软骨下骨骨髓水肿体积、白细胞介素6、白细胞介素8、C-反应蛋白、降钙素原、血小板衍生生长因子、转化生长因子β1水平、疗效方面比较差异均有显著性意义(P<0.05),其中B组的疗效总有效率为90%,比A组总有效率(85%)高(P<0.05);④年龄(OR=1.589,95%CI:0.305-1.252,P=0.036)、白细胞介素6(OR=1.737,95%CI:0.974-5.254,P=0.049)、白细胞介素8(OR=1.385,95%CI:1.066-4.355,P=0.034)、C-反应蛋白(OR=1.957,95%CI:1.323-2.178,P=0.035)、转化生长因子β1(OR=1.459,95%CI:0.897-2.455,P=0.038)、T1ρ值(OR=1.687,95%CI:0.854-3.321,P=0.026)、T2值(OR=1.843,95%CI:0.657-2.454,P=0.036)、并发症(OR=1.719,95%CI:0.654-3.464,P=0.019)、距骨骨软骨损伤分型(OR=3.789,95%CI:1.023-5.897,P=0.028)均是影响患者术后复发的独立危险因素;而微骨折手术(OR=0.751,95%CI:0.321-1.264,P=0.012)、自体骨软骨移植(OR=0.649,95%CI:0.246-1.356,P=0.023)、是中长期随访术后复发的独立保护因素;⑤当T1ρ值≤35 ms时,术后复发的风险迅速降低;当T1ρ值>35 ms时,术后复发风险迅速升高;⑥进一步逐步回归分析显示上述9个危险因素与术后复发的关联最紧密,得出术后复发的公式,利用回归方程计算术后复发的可能性;P=0.75时,约登指数值最大,为77.728,提示模型预测效果较好;⑦提示术前T1ρ技术定量评估可有效指导术式的选择,提高手术成功率和患者生活质量。

关节镜下关节清理联合微骨折技术对膝关节骨折患者肢体运动功能的影响

目的 探讨关节镜下关节清理联合微骨折技术治疗膝关节骨折患者的效果。方法 70例膝关节骨折患者随机分为两组,对照组采用关节镜下关节清理手术治疗,观察组在对照组基础上采用微骨折技术治疗,比较两组的膝关节功能、疼痛反应和下肢运动功能。结果 观察组治疗后的HSS评分、下肢Fugl-Meyer评分均高于对照组,治疗后1周内的VAS评分均低于对照组(P <0.05)。结论 关节镜下关节清理联合微骨折技术治疗膝关节骨折可提升患者的膝关节功能,减轻术后疼痛,提升下肢运动能力。

碳酸盐岩储层高酸溶多级架桥暂堵型钻井完井液体系

以顺北二区碳酸盐岩储层为研究对象,通过岩心裂缝稳定性校正评价了储层敏感性,开展了现用钻井液伤害评价,明确了储层损害主控因素为应力敏感伤害和固相伤害,2种伤害因素累计占比达78.07%。采取“钻井可暂堵、完井可解堵”理念和保护微裂缝为主的储层保护思路,根据裂缝架桥封堵理论,研选了高酸溶固相封堵材料耦合可降解纤维关键材料。通过抗温、抗盐抗钙、沉降稳定性、配伍性及储层保护性能评价,形成了耐高温180℃多级架桥储层保护钻井完井液体系,其承压超过10 MPa,酸化后渗透率恢复率均值可达96.86%,相对常规不含酸溶暂堵材料体系提高了16.23%,具有强封堵、高返排的特点,有望减轻顺北二区碳酸盐岩储层的损害。

基于ResNet残差神经网络识别的深部煤层显微组分和微裂缝分类——以鄂尔多斯盆地石炭系本溪组8~#煤层为例

显微组分和微裂缝是煤储层重要的微观特征,影响煤储层产气能力和力学性质。采集鄂尔多斯盆地深部煤层气井石炭系本溪组8^(#)煤层样品,运用ResNet残差神经网络识别方法,研究了显微组分和微裂缝发育特征。在煤样305个显微组分和65个微裂缝图样本研究的基础上,建立了基于残差神经网络识别的煤岩显微组分和微裂缝识别方法,并利用残差神经网络技术对镜下数据进行反演,构建了深部煤储层显微组分和微裂缝的识别和分类模型。结合地质特征和聚类算法结果联合验证,模型具有可靠性。显微组分预测准确率为0.90,微裂缝预测准确率为0.80,可以有效预测煤岩显微组分和微裂缝类型。模型识别与预测表明裂缝形态与显微组分具有相关关系。裂缝的发育与显微组分中的镜质组关系最大,裂缝类别和数量的预测结果与显微组分发育的相吻合。

渤中凹陷中生界火山岩储层裂隙发育程度实验研究:以安山岩为例

渤海湾盆地中生界火山岩发育广泛,但含油气性横向变化较大,失利井较多,勘探风险大,了解火山岩潜山储层内部裂隙发育程度及规律可为中生界火山岩潜山勘探提供理论依据。本文选取中生界安山岩,开展不同构造环境下岩石微裂隙发育程度实验,分析安山岩在不同应力状态下微裂隙发育规模、频率以及微裂隙空间分布,探讨张性和压性构造应力环境下中生界火山岩微裂隙发育能力及空间展布规律。实验结果表明:安山岩在压性和张性环境下均有微裂隙发育;安山岩在较低的压应力作用下产生大量微裂隙,微裂隙发育规模不随应力增大而升高,其原因可能是安山岩本身含有大量先存构造缝、溶蚀缝和溶蚀孔,受较小的应力后“再活化”产生微裂隙;结合渤中凹陷的构造演化过程,安山岩经历了燕山早期北东向压扭、中期伸展,燕山晚期右旋压扭及喜山期伸展,导致其内部裂隙较为发育,其运储能力提升,具备成为优质储层的基本条件。