Basin-and Mountain-Building Dynamic Model of “Ramping-Detachment-Compression” in the West Kunlun-Southern Tarim Basin Margin

Analysis of the deformation structures in the West Kunlun-Tarim basin-range junction belt indicates that sediments in the southwestern Tarim depression were mainly derived from the West Kunlun Mountains and that with time the region of sedimentation extended progressivdy toward the north. Three north-underthrusting （subducting）, steep-dipping, high-velocity zones （bodies） are recognized at depths, which correspond to the central West Kunlun junction belt （bounded by the Kiida-Kaxtax fault on the north and Bulungkol-Kangxiwar fault on the south）, Quanshuigou fault belt （whose eastward extension is the Jinshajiang fault belt） and Bangong Co-Nujiang fault belt. The geodynamic process of the basin-range junction belt generally proceeded as follows： centering around the magma source region （which largely corresponds with the Karatag terrane at the surface）, the deep-seated material flowed and extended from below upward and to all sides, resulting in strong deformation （mainly extension） in the overlying lithosphere and even the upper mantle, appearance of extensional stress perpendicular to the strike of the orogenic belt in the thermal uplift region or at the top of the mantle diapir and localized thickening of the sedimentary cover （thermal subsidence in the upper crust）. Three stages of the basin- and mountain-forming processes in the West Kunlun-southern Tarim basin margin may be summarized： （1） the stage of Late Jurassic-Early Cretaceous rampingrapid uplift and rapid subsidence, when north-directed thrust propagation and south-directed intracontinental subduction, was the dominant mechanism for basin- and mountain-building processes; （2） the stage of Late Cretaceous-Paleogene deep-level detachment-slow uplift and homogeneous subsidence, when the dominant mechanism for the basin- and mountain-forming processes was detachment （subhorizontal north-directed deep-level ductile shear） and its resulting lateral propagation of deep material; and （3） the stage of Neogene-present compression-rapid uplift and strong subsidence, when the basin- and mountain-forming processes were simultaneously controlled by north-vergent thrust propagation and compression. The authors summarize the processes as the “ramping-detachment-compression basin- and mountain-forming dynamic model”. The basin-range tectonics was initiated in the Late Jurassic, the Miocene-Pliocene were a major transition period for the basin- and mountain-forming mechanism and the terminal early Pleistocene tectonic movement in the main laid a foundation for the basin-and-mountain tectonic framework in the West Kunlun-southern Tarim basin margin.

Porosity, permeability and rock mechanics of Lower Silurian Longmaxi Formation deep shale under temperature-pressure coupling in the Sichuan Basin, SW China

To investigate the porosity, permeability and rock mechanics of deep shale under temperature-pressure coupling, we selected the core samples of deep shale from the Lower Silurian Longmaxi Formation in the Weirong and Yongchuan areas of the Sichuan Basin for porosity and permeability experiments and a triaxial compression and sound wave integration experiment at the maximum temperature and pressure of 120 ℃ and 70 MPa. The results show that the microscopic porosity and permeability change and the macroscopic rock deformation are mutually constrained, both showing the trend of steep and then gentle variation. At the maximum temperature and pressure, the porosity reduces by 34%–71%, and the permeability decreases by 85%–97%. With the rising temperature and pressure, deep shale undergoes plastic deformation in which organic pores and clay mineral pores are compressed and microfractures are closed, and elastic deformation in which brittle mineral pores and rock skeleton particles are compacted. Compared with previous experiments under high confining pressure and normal temperature,the experiment under high temperature and high pressure coupling reveals the effect of high temperature on stress sensitivity of porosity and permeability. High temperature can increase the plasticity of the rock, intensify the compression of pores due to high confining pressure, and induce thermal stress between the rock skeleton particles, allowing the reopening of shale bedding or the creation of new fractures along weak planes such as bedding, which inhibits the decrease of permeability with the increase of temperature and confining pressure. Compared with the triaxial mechanical experiment at normal temperature, the triaxial compression experiment at high temperature and high pressure demonstrates that the compressive strength and peak strain of deep shale increase significantly due to the coupling of temperature and pressure. The compressive strength is up to 435 MPa and the peak strain exceeds 2%, indicating that high temperature is not conducive to fracture initiation and expansion by increasing rock plasticity. Lithofacies and mineral composition have great impacts on the porosity, permeability and rock mechanics of deep shale. Shales with different lithologies are different in the difficulty and extent of brittle failure. The stress-strain characteristics of rocks under actual geological conditions are key support to the optimization of reservoir stimulation program.

Overpressure origins and evolution in deep-buried strata:A case study of the Jurassic Formation,central Junggar Basin,western China

Overpressure is significant to the exploration and exploitation of petroleum due to its influence on hydrocarbon accumulation and drilling strategies.The deep-burial hydrocarbon reservoirs of Jurassic strata in the central Junggar Basin are characterized by intensive overpressure,whose origins are complex and still unclear.In this study,Bowers'method and sonic velocity-density crossplot method based on well logging data were used as a combination for overpressure judgements in geophysics.Furthermore,the corresponding geological processes were analysed in quality and quantity to provide a rational comprehension of the overpressure origins and the model of overpressure evolution and hy-drocarbon accumulation processes.The results showed that hydrocarbon generation in the Jurassic source rocks led to overpressure in the mudstones,while hydrocarbon generation in Permian source rocks led to overpressure in the sandstone reservoirs in Jurassic strata by vertical pressure transfer.The burial and thermal history indicated that the aquathermal effect of pore fluids by temperature increase in deep strata is also an important origin of overpressure,while disequilibrium compaction may not be the dominant cause for the overpressure in deep-buried strata.Furthermore,the continuous tectonic compression in both the north-south and west-east trends from the Jurassic period to the present may also have enhanced the overpressure in deep strata.Meanwhile,the developed faults formed by intensive tectonic compression led to pressure transfer from source rocks to the Jurassic reservoirs.Overpressured geofluids with hydrocarbons migrated to sandstone reservoirs and aggravated the over-pressure in the Jurassic strata.To conclude,the intensive overpressure in the central Junggar Basin is attributed to the combination of multiple mechanisms,including hydrocarbon generation,the aqua-thermal effect,tectonic compression and pressure transfer.Furthermore,the developed overpressure indicated hydrocarbon migration and accumulation processes and the potential of oil and gas reservoirs in deeply buried strata.We hope this study will provide a systematic research concept for overpressure origin analysis and provide guidance for petroleum exploration and exploitation in deep-buried strata.

QUANTITATIVE SUBSIDENCE ANALYSIS OFTHE TENSIVE BASIN AND COMPRESSIVEMOUNTAIN TYPE DIWA BASIN WITH IMPLICATIONS FOR EPISODIC TECTONIC MOVEMENT AND SEDIMENTATION

This paper presents a quantitative analysis of Jurassic-Quaternary basement subsidence in the Delingha basin, a tensile basin and compressive mountain type diwa basin, and corrected for local sediment loading. Subsidence patterns have been investigated for the effects of erosion induced uplift by means of analytical estimation. The history of the Delingha basin has been divided into four stages: 204(?)~130 Ma (SⅠ ), 130~95 Ma (SⅡ ), 67~35 Ma (SⅢ ) and 35~0 Ma (SⅣ ), recording episodic tectonics and sedimentation respectively.

压缩感知提频技术在莺琼盆地W1井区地震资料处理中的应用

针对莺琼盆地W1井区地震资料分辨率低、砂体展布及叠置关系复杂的问题,综合莺琼盆地W1井区三个年份的原始资料,设计了一套包括预处理、去噪处理、偏移以及偏后处理的整套资料处理流程。在偏后处理中将压缩感知提频技术应用于叠前深度偏移剖面上,并与蓝色滤波提频技术、零相位反褶积提频技术进行了对比,体现了压缩感知提频技术的优势;运用压缩感知提频技术解决了莺琼盆地W1井区目前存在的地质问题,证明其在莺琼盆地W1井区后续开发实施上的合理性。结果表明:相较于其他两种提频技术,采用压缩感知提频技术可以保护主频以下可靠的低频信息,拓展高频,提高了资料的分辨率。通过压缩感知提频后的地震数据,气水关系更加清晰,砂体的叠置特征得以真实呈现,验证了其对后续油气勘探的指示意义。压缩感知提频技术作为一种新的地震资料处理技术,能够较好地解决地震资料分辨率低、砂体展布及叠置关系复杂等问题,值得在实际地震资料处理中推广应用。

有效应力恢复条件下水力压裂后煤层气分区渗流特征

目前煤层气单井主要通过水力压裂技术来提高产量,但水力压裂技术会导致煤层裂缝出现分区现象,在有效应力作用下不同裂缝分区的渗流特征将直接影响煤层气抽采效果。为了更好地研究有效应力对不同裂缝分区渗流特征的影响,以沁水盆地煤样为例,设计了完整煤样、微裂缝煤样和贯穿裂缝煤样的串、并联多腔体试验方法,分析了水力压裂后煤层气的横向沿区渗流和纵向跨区渗流,构建了有效应力影响下的不同损伤煤岩体串、并联渗透率模型,分析了有效应力恢复过程中水力压裂不同致裂分区的渗流特征,并预测了不同致裂深度和扰动范围下的煤层总体渗透性。研究结果表明:(1)随着有效应力的恢复,串、并联试验的总流量均呈现负指数形式的衰退;(2)在并联试验中,穿过完整煤样的流量占比极少,随着有效应力的恢复,穿过微裂缝煤样的流量占比逐渐增加,而贯穿裂缝煤样的流量逐渐减小,并逐渐趋于相等;(3)纵向渗流总渗透率小于横向渗流,纵向渗流总渗透性的变化受完整煤样的渗透性影响较大,而横向渗流总渗透性取决于贯穿裂缝煤样渗透性;(4)基于横纵向渗透率的大小,可以将煤层气产期曲线划分为单峰型与双峰型。结论认为,提高水力裂缝深度与射孔孔眼周围裂缝宽度有利于提高煤层气的抽采量,该认识可以为煤层气水力压裂参数设计提供参考,有助于推动煤层气的效益开发。

Changes of Late Mesozoic Tectonic Regimes around the Ordos Basin(North China)and their Geodynamic Implications

A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates （the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west） towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton.

Characteristics,origin and controlling effects on hydrocarbon accumulation of overpressure in foreland thrust belt of southern margin of Junggar Basin,NW China

Aiming at the differential distribution of overpressure in vertical and lateral directions in the foreland thrust belt in the southern margin of Junggar Basin,the study on overpressure origin identification and overpressure evolution simulation is carried out.Based on the measured formation pressure,drilling fluid density and well logging data,overpressure origin identification and overpressure evolution simulation techniques are used to analyze the vertical and lateral distribution patterns of overpressure,genetic mechanisms of overpressure in different structural belts and causes of the differential distribution of overpressure,and the controlling effects of overpressure development and evolution on the formation and distribution of oil and gas reservoirs.The research shows that overpressure occurs in multiple formations vertically in the southern Junggar foreland thrust belt,the deeper the formation,the bigger the scale of the overpressure is.Laterally,overpressure is least developed in the mountain front belt,most developed in the fold anticline belt,and relatively developed in the slope belt.The differential distribution of overpressure is mainly controlled by the differences in disequilibrium compaction and tectonic compression strengths of different belts.The vertical overpressure transmission caused by faults connecting the deep overpressured system has an important contribution to the further increase of the overpressure strength in this area.The controlling effect of overpressure development and evolution on hydrocarbon accumulation and distribution shows in the following aspects:When the strong overpressure was formed before reservoir becoming tight overpressure maintains the physical properties of deep reservoirs to some extent,expanding the exploration depth of deep reservoirs;reservoirs below the overpressured mudstone cap rocks of the Paleogene Anjihaihe Formation and Lower Cretaceous Tugulu Group are main sites for oil and gas accumulation;under the background of overall overpressure,both overpressure strength too high or too low are not conducive to hydrocarbon enrichment and preservation,and the pressure coefficient between 1.6 and 2.1 is the best.

Earthquake-related Tectonic Deformation of Soft-sediments and Its Constraints on Basin Tectonic Evolution

The authors introduced two kinds of newly found soft-sediment deformation-synsedimentary extension structure and syn-sedimentary compression structure, and discuss their origins and constraints on basin tectonic evolution. One representative of the syn-sedimentary extension structure is syn-sedimentary boudinage structure, while the typical example of the syn-sedimentary compression structure is compression sand pillows or compression wrinkles. The former shows NW-SE-trendlng contemporaneous extension events related to earthquakes in the rift basin near a famous Fe-Nb-REE deposit in northern China during the Early Paleozoic （or Mesoproterozoic as proposed by some researches）, while the latter indicates NE-SW-trending contemporaneous compression activities related to earthquakes in the Middle Triassic in the Nanpanjiang remnant basin covering south Guizhou, northwestern Guangxi and eastern Yunnan in southwestern China. The syn-sedimentary boudinage structure was found in an earthquake slump block in the lower part of the Early Paleozoic Sailinhudong Group, 20 km to the southeast of Bayan Obo, Inner Mongolia, north of China. The slump block is composed of two kinds of very thin layers-pale-gray micrite （microcrystalline limestone） of 1-2 cm thick interbedded with gray muddy micrite layers with the similar thickness. Almost every thin muddy micrite layer was cut into imbricate blocks or boudins by abundant tiny contemporaneous faults, while the interbedded micrite remain in continuity. Boudins form as a response to layer-parallel extension （and/or layer-perpendicular flattening） of stiff layers enveloped top and bottom by mechanically soft layers. In this case, the imbricate blocks cut by the tiny contemporaneous faults are the result of abrupt horizontal extension of the crust in the SE-NW direction accompanied with earthquakes. Thus, the rock block is, in fact, a kind of seismites. The syn-sedimentary boudins indicate that there was at least a strong earthquake belt on the southeast side of the basin during the early stage of the Sailinhudong Group. This may be a good constraint on the tectonic evolution of the Bayan Obo area during the Early Paleozoic time. The syn-sedimentary compression structure was found in the Middle Triassic flysch in the Nanpanjiang Basin. The typical structures are compression sand pillows and compression wrinkles. Both of them were found on the bottoms of sand units and the top surface of the underlying mud units. In other words, the structures were found only in the interfaces between the graded sand layer and the underlying mud layer of the flysch. A deformation experiment with dough was conducted, showing that the tectonic deformation must have been instantaneous one accompanied by earthquakes. The compression sand pillows or wrinkles showed uniform directions along the bottoms of the sand layer in the flysch, revealing contemporaneous horizontal compression during the time between deposition and diagenesis of the related beds. The Nanpanjiang Basin was affected, in general, with SSW-NNE compression during the Middle Triassic, according to the syn-sedimentary compression structure. The two kinds of syn-sedimentary tectonic deformation also indicate that the related basins belong to a rift basin and a remnant basin, respectively, in the model of Wilson Cycle.

THE TECTONIC PROCESS AND THE FILLING OF TERRESTRIAL BASIN

The relation and unity of the tectonic process and sedimentation is being paid a good deal of attention. It is very obvious that the sedimentary process of the terrestrial basin is controlled by tectogenesis. The sedimentary evolution of the basin is the reflection of the tectonic evolution . The sedimentary process of the terrestrial basin has unique characteristics.(1) The scope of the terrestrial basin is mainly controlled by the fault zones.(2) The regional tectonic cycle obviously controls the sedimentary sequence boundary of the terrestrial basin. The periodicity of tectogenesis causes the periodic change of the sedimentary sequence.(3) The sedimentary model of the terrestrial basin is obviously controlled by the tectonic framework.(4) There are many surprise sedimentary events in sedimentary formation of the terrestrial basin.(5) Owing to the influence of the tectonization, the deformation frequently occurs in the sedimentary deposit.(6) Because the sediments of the terrestrial basin have the short\|distance transport, the sediments have the low mature index.(7) There are more sedimentary centres, more matter\|sources, narrow sedimentary facies\|zone and the quick facies change in the terrestrial basin.According to the background of the tectonic dynamics, the terrestrial basin can be divided into the extension basin, the compression basin and the shear basin. The three basins differ greatly in the sedimentary characteristics. The extension basin is usually directed at rift basin. The border of the extension basin is mainly the normal fault or growth fault. The plane shape of the extension is zone\|shape. The sedimentary deposit of the extension basin has not strong deformation. The thickness of the sediment on the downthrow wall is greater than that the sediment on the upcast wall. The periodic change of the tectogenesis causes the enlarging or the contract of the extension basin.

Effects of Lateral Variation in Vegetation and Basin ‘Dome' Shape on Tropical Lowland Peat Stabilisation in the Kota Samarahan-Asajaya Area, West Sarawak, Malaysia

Field surveys indicate lateral variation in peat humification levels （von Post） in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of tropical lowland peat domes.Cement-peat stabilisation can be enhanced by adding mineral soil fillers （silt,clays and fine sands） obtained from Quaternary floodplain deposits and residual soil （weathered schist）.The unconfined compressive strength （UCS） of the stabilised cement-mineral soil fifler-peat mix increases with the increased addition of selected mineral soil filler.Lateral variation in the stabilised peat strength （UCS） in the top 0 to 0.5 m layer was found from the margin towards the centre of the tropical lowland peat dome.The variations in the UCS of stabilised tropical lowland peats along a gradient from the periphery towards the centre of the peat dome are most likely caused by a combination of factors due to variations in the mineral soil or ash content of the peat and horizontal zonation or lateral variation in the dominant species of the plant assemblages （due to successive vegetation zonation of the peat swamp forest from the periphery towards the centre of the tropical lowland peat dome）.

Geomechanical Characterization of Sandstones Cliffs of Segou (Senegal, West Africa) in the Madina Kouta Basin

This work presents the behavior of Segou sandstones in the laboratory and in the field conditions. Four types of sandstone are collected in the northern part of the Madina Kouta basin (eastern Senegal). These types of specimens are the white sandstones, the red sandstones, the purple sandstones and the sandstones with intercalation of pelites. Uniaxial tests are carried out on these specimens of sandstones. The Young Moduli (E) and the Uniaxial Compression Strengths (Rc) are higher for the white sandstone. Values of the mechanical parameters decrease slightly for red sandstones due to an increase of the amount of pelites in the composition of the rock. Decrease of mechanical parameters is more important for the purple facies due to an important network of fractures. The facies with weaker characteristics corresponds to the sandstones with intercalation of pelites. This is due to the soft nature of the pelites. The slope stability of the Cliff sides depends also on to these characteristics.

Overpressure and gas charging in tight sandstone:Xujiahe Formation,northeastern Sichuan Basin

Overpressure is a key factor for oil and gas charging in tight reservoirs,but it is still a challenge to evaluate the overpressure evolution and its control on oil and gas charging.Taking Xujiahe Formation in the northeastern Sichuan Basin as an example,this paper presented a method for evaluating overpressure and its effect on natural gas charging in tight sandstone in compressional basin.The abnormally high pressure and its causes were analyzed by measured data and logging evaluation.Theoretical calculation and PVT simulation were used to investigate the amounts of overpressure resulted from hydrocarbon generation and tecto nic compression,respectively.Then the source rock-reservoir pressu re differences were calculated and the characteristics of natural gas charging during the natural gas charging periods were analyzed.It was revealed that hydrocarbon generation and tectonic compression were the main causes of the overpressure.The overpressure of both source rocks and reservoir exhibited a gradually increasing trend from Middle Jurassic to Early Cretaceous(J2-K1),then decreased since Later Cretaceous(K2),and some of that preserved to now.The contributions of the hydrocarbon generation and tectonic compression to overpressure were different in different periods.The residual pressure difference between the source rocks and the reservoir is the major driving force for tight sandstone gas charging.The main hydrocarbon generating area of the source rocks and the area of high driving force were major natural gas enrichment areas,and the driving force determined the natural gas charging space in the pore throat system of the reservoir.This research helps evaluate the overpressure and pressure difference between source rocks and reservoir in compressed basin,as well as investigate the effective pore throat space of tight gas charging by the driver of overpressure.

Strain data recorded in Xinjiang and their bearing on Tianshan’s uplift/shortening and Tarim basin’s rotation

Based on the continuous strain data recorded in Xinjiang since 1985, we discuss the mechanisms of Tianshan＇ s uplift and Tarim basin＇ s clockwise rotation. The results indicate ： 1 ） The principal - compression directions in Tianshan are nearly NS, and their intersection angles with regional structures and mountains are nearly perpendicular, which is in accordance with Tianshan＇ s uplift and crustal shortening. 2）The principal compressions around Tarim basin tend to facilitate the regional faults＇ left-lateral strike-slip movements and the basin＇ s clockwise rotation. These phenomena of uplift/shortening and rotation are fundamentally the re- suits of India plate＇ s northward push on Euro-Asia plate, and the associated Pamir arc ＇ s rapid northward movement and regional blocks＇ interaction.

Mechanical properties of Michigan Basin’s gypsum before and after saturation

The stability analysis of an abandoned underground gypsum mine requires the determination of the mine pillar’s strength.This is especially important for flooded abandoned mines where the gypsum pillars become saturated and are subjected to dissolution after flooding.Further,mine pillars are subjected to blast vibrations that generate some level of macro- and micro-fracturing.Testing samples of gypsum must,therefore,simulate these conditions as close as possible.In this research,the strength of gypsum is investigated in an as-received saturated condition using uniaxial compressive strength (UCS),Brazilian tensile strength (BTS) and point load index (PLI) tests.The scale effect was investigated and new correlations were derived to describe the effect of sample size on both UCS and BTS under dry and saturated conditions.Effects of blasting on these parameters were observed and the importance of choosing the proper samples was discussed.Finally,correlations were derived for both compressive and tensile strengths under dry and saturated conditions from the PLI test results,which are commonly used as a simple substitute for the indirect determination of UCS and BTS.

鄂尔多斯盆地西缘麻黄山西工区走滑断层构造特征与三维离散元数值模拟

麻黄山西工区位于鄂尔多斯盆地西缘冲断带的前端部位,以石炭—二叠系煤系滑脱层为界划分为上、下两套构造变形层,并受燕山期走滑断层作用表现出分段变形特征。深层原地构造系统沙窝子断层以北的正断层构成多米诺组合型式,而沙窝子与圈湾子断层之间的正断层组合成堑垒式。浅层逆冲推覆构造系统以NEE向芦沟子—新泉井断层为界,划分为变形特征差异明显的南、北两段,北段相对南段变形强烈。三维离散元数值模拟实验结果显示,麻黄山西工区上、下构造变形层内发育的走滑断层均为调节差异挤压作用形成的撕裂断层,断层走向与挤压应力方向基本一致。原地构造系统的先存正断层在走滑作用下产生牵引,邻近走滑断层的正断层走向发生明显偏转。逆冲推覆构造系统北段山前强烈冲断作用对盆内产生较为明显影响;而南段山前冲断作用并未对盆内产生明显影响,仅发育少量小规模逆断层。相较于二维模拟,三维模拟能够实现平面与剖面的综合分析,完整认识上、下构造变形层多条走滑断层的变形过程与形成机制,为麻黄山西工区的油气勘探提供基础地质理论指导。

温压耦合作用下四川盆地深层龙马溪组页岩孔渗和岩石力学特征

为了研究温压耦合变化对深层页岩孔隙度、渗透率和岩石力学特征的影响,选择四川盆地威荣和永川地区下志留统龙马溪组深层页岩岩心样品,设计开展温压条件的上限为120℃、70 MPa的孔渗实验和三轴压缩岩石力学—声波一体化实验。研究结果表明:(1)微观上的孔渗变化与宏观上的岩石变形相互约束,均呈现先快后缓的变化特征,最大温压实验条件下孔隙度降低34%~71%、渗透率降低85%~97%。随着温压的升高,深层页岩经历了以有机质孔、黏土矿物孔被压缩和微裂缝受压闭合的塑性变形和脆性矿物孔、岩石骨架颗粒本体被压缩的弹性变形;(2)与常温高围压实验对比,高温对孔渗应力敏感的影响显著。高温通过增加岩石塑性,加剧高围压对孔隙的压缩,同时引发岩石骨架颗粒间产生热应力,页岩层理易重新开启或沿层理等软弱面产生新缝,使得页岩渗透率随温度和围压升高而降低的程度减弱;(3)与常温三轴力学实验对比,深层页岩在高温高压耦合作用下,抗压强度和峰值应变量显著增加,抗压强度最高达435 MPa、峰值应变超过2%,说明高温增加了岩石塑性,不利于页岩的破裂和裂缝扩展;(4)岩相和矿物组分对深层页岩孔渗和岩石力学特征具有重要影响。不同岩性页岩发生脆性破坏的难度和充分程度不同,实际地质条件下页岩的应力应变特征是压裂方案优化调整的重要依据。

柴达木盆地大风山凸起地层压力预测及成因分析

地层超压预测对油气成藏的研究具有重要意义。通过测井曲线组合、声波速度-垂向有效应力交会图、声波速度-密度交会图和超压综合分析等方法,对柴达木盆地大风山凸起各层位的超压成因进行了分析,并对压力预测方法进行了改进。研究结果表明:(1)柴达木盆地大风山凸起下油砂山组地层超压成因为不均衡压实和构造挤压作用;上干柴沟组和下干柴沟组上段超压成因为不均衡压实、构造挤压和超压传递。(2)用单一方法如平衡深度法或伊顿法均无法有效预测研究区的地层压力,基于不同超压成因机制的差异,对下油砂山组地层压力采用平衡深度法计算,对上干柴沟组和下干柴沟组上段则使用伊顿法计算,结果更准确。研究区压力计算结果与实测地层压力的误差小于7.00%,平均误差为4.30%。(3)超压的预测可为油藏描述、储量估算、安全钻井作业提供数据支持。超压是油气运移的动力,可以指示油气运移的方向,估算油气运移距离,对油气成藏的研究具有重要指导意义。

黄河淤泥固化改性材料力学性能与微观结构试验研究

通过力学强度测试、矿物成分分析、红外光谱测试(FTIR)和电子扫描电镜(SEM)分析等,研究了改性剂模数、改性剂掺量及养护龄期对黄河流域河库底淤泥固化改性土的力学性能、矿物组成、微观结构和水化产物成分的影响。结果表明:改性剂模数、改性剂掺量和养护龄期对固化淤泥试块的力学性能影响显著,试件抗压强度随改性剂掺量和养护龄期的增加而增长,抗压强度最高达7.13 MPa;改性后淤泥中黏土矿物与改性剂反应生成絮状地聚物凝胶,材料结构更加致密均匀。

空气源热泵冷热水机组应用于长江流域供暖的适应性分析及节能性提升

针对空气源热泵冷热水机组在长江流域的供暖应用,从气候特征、供暖水温需求、负荷需求等方面进行了适应性分析,从系统设计及识霜、抑霜控制等方面提出了节能性提升方案,并通过实验验证了提升效果。结果表明:出水温度35~50℃可有效满足供暖要求,同时能效较佳;模块化变频单级压缩系统能够较好地满足实际使用需求,可有效提升综合性能系数;基于最佳效率的压缩机加、卸载调度控制及基于最小换热温差的识霜、抑霜控制,可以较好地应对负荷需求,使机组运行在最佳效率点,制热工况性能系数最大提升20%。