Quantitative effect of kerogen type on the hydrocarbon generation potential of Paleogene lacustrine source rocks,Liaohe Western Depression,China

Kerogen types exert a decisive effect on the onset and capacity of hydrocarbon generation of source rocks.Lacustrine source rocks in the Liaohe Western Depression are characterized by thick deposition,high total organic carbon(TOC)content,various kerogen types,and a wide range of thermal maturity.Consequently,their hydrocarbon generation potential and resource estimation can be misinterpreted.In this study,geochemical tests,numerical analysis,hydrocarbon generation kinetics,and basin modeling were integrated to investigate the differential effects of kerogen types on the hydrocarbon generation potential of lacustrine source rocks.Optimized hydrocarbon generation and expulsion(HGE)models of different kerogen types were established quantitatively upon abundant Rock-Eval/TOC/vitrinite reflectance(R_(o))datasets.Three sets of good-excellent source rocks deposited in the fourth(Es4),third(Es3),and first(Es1)members of Paleogene Shahejie Formation,are predominantly types I-II_(1),II_(1)-II_(2),and II-III,respectively.The activation energy of types I-II_(2)kerogen is concentrated(180-230 kcal/mol),whereas that of type III kerogen is widely distributed(150-280 kcal/mol).The original hydrocarbon generation potentials of types I,II_(1),II_(2),and III kerogens are 790,510,270,and 85 mg/g TOC,respectively.The Ro values of the hydrocarbon generation threshold for type I-III source rocks gradually increase from 0.42%to 0.74%,and Ro values of the hydrocarbon expulsion threshold increase from 0.49%to 0.87%.Types I and II_(1)source rocks are characterized by earlier hydrocarbon generation,more rapid hydrocarbon expulsion,and narrower hydrocarbon generation windows than types II_(2)and III source rocks.The kerogen types also affect the HGE history and resource potential.Three types(conventional,tight,and shale oil/gas)and three levels(realistic,expected,and prospective)of hydrocarbon resources of different members in the Liaohe Western Depression are evaluated.Findings suggest that the Es3 member has considerable conventional and unconventional hydrocarbon resources.This study can quantitatively characterize the hydrocarbon generation potential of source rocks with different kerogen types,and facilitate a quick and accurate assessment of hydrocarbon resources,providing strategies for future oil and gas exploration.

Master crack types and typical acoustic emission characteristics during rock failure

Acoustic emission(AE)signals contain substantial information about the internal fracture characteristics of rocks and are useful for revealing the laws governing the release of energy stored therein.Reported here is the evolution of rock failure with diferent master crack types as investigated using Brazilian splitting tests(BSTs),direct shear tests(DSTs),and uniaxial compression tests(UCTs).The AE parameters and typical modes of each fracture type were obtained,and the energy release characteristics of each fracture mechanism were discussed.From the observed changes in the AE parameters,the rock fracture process exhibits characteristics of staged intensifcation.The scale and energy level of crack activity in the BSTs were signifcantly lower than those in the DSTs and UCTs.The proportion of tensile cracks in the BSTs was 65%–75%,while the proportions of shear cracks in the DSTs and UCTs were 75%–85%and 70%–75%,respectively.During the rock loading process under diferent conditions,failure was accompanied by an increased number of shear cracks.The amplitude,duration,and rise time of the AE signal from rock failure were larger when the failure was dominated by shear cracks rather than tensile ones,and most of the medium-and high-energy signals had medium to low frequencies.After calculating the proposed energy amplitude ratio,the energy release of shear cracks was found to exceed that of tensile cracks at the same fracture scale.

A detailed rock density model of the Hong Kong territories

We used the geological map and published rock density measurements to compile the digital rock density model for the Hong Kong territories.We then estimated the average density for the whole territory.According to our result,the rock density values in Hong Kong vary from 2101 to 2681 kg·m^(-3).These density values are typically smaller than the average density of 2670 kg·m^(-3),often adopted to represent the average density of the upper continental crust in physical geodesy and gravimetric geophysics applications.This finding reflects that the geological configuration in Hong Kong is mainly formed by light volcanic formations and lava flows with overlying sedimentary deposits at many locations,while the percentage of heavier metamorphic rocks is very low(less than 1%).This product will improve the accuracy of a detailed geoid model and orthometric heights.

Rock Series and Genetic Types of Granitoids in the Western Kunlun Orogenic Belt,China

A systematic geological and geochemical study was conducted for the granitoids of different periods in the western Kunlun orogenic belt. The study indicates that the granitoids belong to tholeiitic, calc-alkaline, high-K calc-alkaline, alkaline and shoshonitic series, and that there are 5 genetic types, i.e., I-, S-, M-, A- and SH-type, of which SH-type is first put forward in this paper, which corresponds to shoshonitic granitoids.

A New Type of REE Deposit Found in Clay Rock at the Top of the Permian Emeishan Basalt in the Yunnan-Guizhou Area

Objective A set of REE-rich clay rocks is formed at the top of the Emeishan basalt in the eastern Yunnan-Western Guizhou area,accompanied by Nb,Zr,Ga.It is a new type of REE deposit and has great resource potential.This paper introduces its metallogenic conditions and element occurrence states,discusses the genetic mechanism.

Effect of overburden pressure on determination of reservoir rock types using RQI/FZI,FZI^* and Winland methods in carbonate rocks

Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.

New Evidence for Genesis of the Zoige Carbonate-Siliceous-Pelitic Rock Type Uranium Deposit in Southern Qinling:Discovery and Significance of the 64 Ma Intrusions

The carbonaceous-siliceous-argillitic rock type uranium deposit in the Zoige area is located in the northeastern margin of the Tibetan Plateau, and has gained much attention of many geologists and ore deposit experts due to its scale, high grade and abundant associated ores. Because of the insufficient reliable dating of intrusive rocks, the relationship between mineralization and the magmatic activities is still unknown. In order to study this key scientific issue and the ore-forming processes of the Zoige uranium ore field, the LA-ICP-MS zircon U-Pb dating of magmatic rocks was obtained：64.08±0.59 Ma for the granite-prophyry and ~200 Ma for the dolerite. U-Pb dating results of uraninite from the Zoige uranium ore field are mainly concentrated on ~90 Ma and ~60 Ma. According to LA-ICP-MS U-Pb zircon dating, the ages for the dolerite, porphyry granite and granodiorite are 200 Ma, 64.08 Ma approximately and 226.5-200.88 Ma, respectively. This indicates that the mineralization has close relationship with activities of the intermediate-acidic magma. The ages of the granite porphyry are consistent with those uraninite U-Pb dating results achieved by previous studies, which reflects the magmatic and ore-forming event during the later Yanshanian. Based on the data from previous researches, the ore bodies in the Zoige uranium ore field can be divided into two categories：the single uranium type and the uranium with polymetal mineralization type. The former formed at late Cretaceous（about 90 Ma）, while the latter, closely related to the granite porphyry, formed at early Paleogene（about 60 Ma）. And apart from ore forming elemental uranium, the latter is often associated with polymetallic elements, such as molybdenum, nickel, zinc, etc.

Uncertainties of landslide susceptibility prediction considering different landslide types

Most literature related to landslide susceptibility prediction only considers a single type of landslide,such as colluvial landslide,rock fall or debris flow,rather than different landslide types,which greatly affects susceptibility prediction performance.To construct efficient susceptibility prediction considering different landslide types,Huichang County in China is taken as example.Firstly,105 rock falls,350 colluvial landslides and 11 related environmental factors are identified.Then four machine learning models,namely logistic regression,multi-layer perception,support vector machine and C5.0 decision tree are applied for susceptibility modeling of rock fall and colluvial landslide.Thirdly,three different landslide susceptibility prediction(LSP)models considering landslide types based on C5.0 decision tree with excellent performance are constructed to generate final landslide susceptibility:(i)united method,which combines all landslide types directly;(ii)probability statistical method,which couples analyses of susceptibility indices under different landslide types based on probability formula;and(iii)maximum comparison method,which selects the maximum susceptibility index through comparing the predicted susceptibility indices under different types of landslides.Finally,uncertainties of landslide susceptibility are assessed by prediction accuracy,mean value and standard deviation.It is concluded that LSP results of the three coupled models considering landslide types basically conform to the spatial occurrence patterns of landslides in Huichang County.The united method has the best susceptibility prediction performance,followed by the probability method and maximum susceptibility method.More cases are needed to verify this result in-depth.LSP considering different landslide types is superior to that taking only a single type of landslide into account.

Mechanism of Pendulum-type wave phenomenon in deep block rock mass

Pendulum-type ( μ wave) wave is a new type of elastic wave propagated with low frequency and low velocity in deep block rock masses. The μ wave is sharply different from the traditional longitudinal and transverse waves propagated in continuum media and is also a phenomenon of the sign-variable reaction of deep block rock masses to dynamic actions, besides the Anomalous Low Friction (ALF) phenomenon. In order to confirm the existence of the μ wave and study the rule of variation of this μ wave experimentally and theoretically, we first carried out one-dimensional low-speed impact experiments on granite and cement mortar blocks and continuum block models with different characteristic dimensions, based on the multipurpose testing system developed by us independently. The effects of model material and dimensions of models on the propagation properties of 1D stress wave in blocks medium are discussed. Based on a comparison and analysis of the propagation properties (acceleration amplitudes and Fourier spectra) of stress wave in these models, we conclude that the fractures in rock mass have considerable effect on the attenuation of the stress wave and retardarce of high frequency waves. We compared our model test data with the data of in-situ measurements from deep mines in Russia and their conclusions. The low-frequency waves occurring in blocks models were validated as Pendulum-type wave. The frequencies corresponding to local maxima of spectral density curves of three-directional acceleration satisfied several canonical sequences with the multiple of 2～(1/2), most of those frequencies satisfied the quantitative expression (2～(1/2))i V p/2△ .

Investigation of Microfacies—Electrofacies and Determination of Rock Types on the Aptian Dariyan Formation NW Persian Gulf

Dariyan (Shuaiba) Formation is one of the main reservoir units in the Persian Gulf and South Western Iran. The microfacies and depositional environment of this formation is been investigated in the current study and influencing factors in reservoir characteristics have been discussed for Dariyan reservoir in the Soroush oil field. Facies analysis conducted on core and cutting samples indicated that Dariyan Formation is mainly deposited on a carbonate ramp setting with a shallow intra shelf basin. In addition, it has been demonstrated that facies changes reflect the main controls of the tectonic and climate (sea level fluctuations) during the deposition of these sediments. To determine the reservoir unites in this formation, 5 electrofacies were determined by neural network method that it is using different petrophysical logs (i.e. GR, PHIE and SWE). Using rock typing as the best way to establish an association between the various collected data (e.g. logs and cores) and geological descriptions 4 hydraulic flow units or rock types, determined on the basis of the Flow Zone Indicator (FZI) method in the Dariyan Formation of the Soroush field. Establishing a correlation between microfacies and rock types, the carbonate zones with moderate to good reservoir properties and also the intervals with the highest reservoir quality were determined.

Geochemical Characteristics of the Jinjiazhuang Ultrabasic Rock-Type Gold Deposit in Chicheng County, Hebei Province

The Jinjiazhuang gold deposit occurs in the Zhangjiakou gold field, Northwest Hebei. The ore bodies are mostly hosted in Xiaozhangjiakou ultrabasic rocks dominated by diopsidite. Electron microprobe analyses indicate that the deposit is characterized by the enrichment of some platinum group elements in principal metallic minerals such as chalcopyrite, galena, sphalerite and pyrite, and the presence of millerite. Stable isotope studies show that carbon, sulfur and most of the metallogenic elements were probably derived largely from the host Xiaozhangjiakou ultrabasic rocks and that it is possible that the ore\|forming fluid was predominated by meteoric water.

Impact of microorganism degradation on hydrocarbon generation of source rocks:A case study of the Bozhong Sag,Bohai Bay Basin

The discovery of the Bozhong 19-6 gas field,the largest integrated condensate gas field in the eastern China in 2018,opened up a new field for the natural gas exploration deep strata in the Bohai Bay Basin,demonstrating there is a great potential for natural gas exploration in oil-type basins.The ethane isotope of the Bozhong 19-6 condensate gas is heavy,showing the characteristics of partial humic gas.In this paper,aimed at the source rocks of the Bozhong 19-6 gas field in the Bohai Bay Basin,the characteristics of the source rocks in the Bozhong 19-6 structural belt were clarified and the reason are explained from impact of microorganism degradation on hydrocarbon generation of source rocks why the condensate oil and gas had heavy carbon isotope and why it showed partial humic characteristics was explored based on the research of parent materials.The following conclusions were obtained:The paleontology of the Bozhong 19-6 structural belt and its surrounding sub-sags is dominated by higher plants,such as angiosperm and gymnosperm.During the formation of source rocks,under the intensive transformation of microorganism,the original sedimentary organic matter such as higher plants was degraded and transformed by defunctionalization.Especially,the transformation of anaerobic microorganisms on source rocks causes the degradation and defunctionalization of a large number of humic products such as higher plants and the increase of hydrogen content.The degradation and transformation of microorganism don't transform the terrestrial humic organic matter into newly formed“sapropel”hydrocarbons,the source rocks are mixed partial humic source rocks.As a result,hydrogen content incrased and the quality of source rocks was improved,forming the partial humic source rocks dominated by humic amorphous bodies.The partial humic source rocks are the main source rocks in the Bozhong 19-6 gas field,and it is also the internal reason why the isotope of natural gas is heavy.

东昆仑大格勒地区碱性岩-碳酸岩型铌矿勘查进展及找矿前景

铌广泛应用在冶金工业、原子能工业、航空航天工业、军事工业、电子工业、超导材料及医疗仪器等方面,是全球高度关注的关键矿产。碱性岩-碳酸岩型矿床赋存了世界上大部分的铌资源,而我国铌资源禀赋差,对外依存度大于90%。2021年青海省地质调查院在东昆仑大格勒地区发现了碱性岩-碳酸岩型铌矿,通过三年的勘查工作,圈定5条铌矿体,矿体延伸长160~1280 m,控制最大斜深800 m,矿体厚度4.3~115.7 m,Nb_(2)O_(5)平均品位0.092%~0.156%,伴生P_(2)O_(5)平均品位3.8%~5.6%。通过资源量估算,Nb_(2)O_(5)推断资源量超过10万吨,已达大型矿床规模。目前铌矿体在走向和倾向上延伸稳定,显示出良好的找矿前景。

塔里木盆地北部奥陶系海相碳酸盐岩断溶体油藏成因类型及特征再认识

前人提出的“断溶体”油藏概念,现已成为海相碳酸盐岩油气藏勘探开发的新目标、新类型。但断溶体油藏与传统的风化壳型喀斯特油藏有显著差别,断溶体储集体类型、结构特点也存在差异。研究断溶体溶蚀作用和构造破裂作用的差异性,将断溶体划分为过溶蚀残留型、破碎+强溶蚀型和强破碎+弱溶蚀型3种类型。研究表明不同成因类型的断溶体油藏,其溶蚀程度、缝洞规模、累产油量、地层能量和缝洞间连通性差异明显。过溶蚀残留型油藏的分布受风化壳不整合面及断裂带的纵向溶蚀作用控制。破碎+强溶蚀型及强破碎+弱溶蚀型油藏的形成和分布与不整合面的发育和构造位置关系不大,主要受溶蚀断裂带“破碎+溶蚀程度”控制,在溶蚀断裂带核部发育规模较大的洞穴,向两侧逐步发育裂缝-孔洞型、裂缝型储层。

Evaluation of Source Rock Potential for Hydrocarbon Generation in Shallow Offshore, Lamu Basin, Kenya

The ever-increasing demand for oil and gas has driven its exploration in rather extreme conditions. In Lamu offshore, which is hitherto underexplored, most of the wells already drilled turned out dry save for a few wells with hydrocarbon shows despite the promising reservoir properties and related geological structures. This, therefore, necessitated a source rock evaluation study in the area to ascertain the presence and potential of the source rock by integrating the geochemical data analysis and petroleum system modeling. The shallow Lamu offshore source rock quantity, quality, and maturity have been estimated through the determination of the total organic carbon (TOC) average values, Kerogen typing, and Rock-Eval pyrolysis measurements respectively. Geochemical data for Kubwa-1, Mbawa-1, Pomboo-1, and Simba-1 were evaluated for determining the source rock potential for hydrocarbon generation. Petroleum system modeling was applied in evaluating geological conditions necessary for a successful charge within a software that integrated geochemical and petrophysical characterization of the sedimentary formations in conjunction with boundary conditions that include basal heat flow, sediment-water interface temperature, and Paleo-water depth. The average TOC of 0.89 wt % in the study area suggests a fair organic richness which seems higher in the late cretaceous (0.98 wt %) than in the Paleocene (0.81 wt %). Vitrinite reflectance and Tmax values in the study area indicate the possible presence of both mature and immature source rocks. Type III Kerogen was the most dominant Kerogen type, and gas shows are the most frequent hydrocarbon encountered in the Lamu Basin with a few cases registering type II/III and type II. The charge properties (i.e. Temperature, transformation ratio, and Vitrinite reflectance) over geologic time at each of the wells have been estimated and their spatial variation mapped as seen from the burial history and depth curves overlaid with temperature, transformation ratio, and Vitrinite reflectance respectively. From the upper cretaceous maturity maps, the results seem to favor near coastal regions where average TOC is about 1.4 wt %, Vitrinite reflectance is more than 0.5%, transformation ratio is more than 10%, and temperatures range from 80°C to 160°C. The results postulate the absence of a definitive effective source rock with a likelihood of having cases of potential and possible source rocks. Moreover, greater uncertainty rests on the source rock’s presence and viability tending toward the deep offshore. Geochemical analysis and petroleum system modeling for hydrocarbon source rock evaluation improved the understanding of the occurrence of the possible and potential source rocks and processes necessary for hydrocarbon generation.

宽高比对煤柱型冲击地压影响规律的实验研究

我国深部煤炭开采日趋复杂,区段煤柱在采动、构造或坚硬顶底板影响下极易诱发煤柱型冲击地压,煤柱型冲击地压的防治已成为煤矿安全高效开采的难题,研究不同宽高比条件下区段煤柱的力学性能及冲击破坏特性对煤柱型冲击地压防治具有积极意义。采用不同宽高比煤样的“岩-煤-岩”组合体进行了单轴压缩实验,通过分析煤岩组合体的冲击倾向性、动态破坏特征、分形维数和声发射特征参数等,研究了宽高比对煤柱冲击破坏的影响规律。结果发现:①煤柱的宽高比对煤岩组合体的冲击倾向性具有显著影响,宽高比不小于2∶1时,其冲击能量指数K_(E)为1.82~2.65,冲击倾向性无明显变化;小于2∶1时冲击倾向性呈先升高后降低的趋势,1∶1时K_(E)最大,达到了15.43。②随宽高比减小,煤岩组合体破坏特征依次表现为:拉压破坏—压剪破坏—拉剪破坏。煤柱宽高比为5∶1~3∶1时,煤岩组合体破坏较为缓慢;宽高比为2∶1时开始出现片状煤屑弹出,冲击破坏剧烈程度较低;宽高比为1∶1和0.75∶1时,具有明显的冲击破坏特性;宽高比为0.5∶1时,煤岩组合体整体稳定性下降,相对0.75∶1煤岩组合体煤柱破坏的剧烈程度降低。③峰后声发射能量释放率与分形维数D变化规律相似,均随宽高比减小呈先升高后降低的趋势。宽高比不小于2∶1时,煤岩组合体破坏过程中能量持续释放时间较长,煤柱破坏平缓;宽高比为1∶1时,能量释放率和D值明显增大,相较宽高比不小于2∶1煤岩组合体的能量释放率增大了约4倍,D值增大了0.18~0.23,煤柱冲击破坏最为剧烈;宽高比0.75∶1煤岩组合体能量释放率与D值分别降低了约10%和0.01,破坏剧烈程度与1∶1煤岩组合体相近;宽高比减小至0.5∶1时,相关参数的降低幅度约为0.75∶1煤岩组合体的6倍,破坏剧烈程度相对较小。研究表明:宽高比对煤柱的冲击破坏具有显著影响,整体上,煤柱冲击破坏剧烈程度随宽高比减小(5∶1~0.5∶1)呈先升高后逐渐降低的趋势;煤柱宽高比大于3∶1时,煤柱冲击危险性相对较小,煤柱宽高比为1∶1和0.75∶1时冲击危险性较大,0.5∶1次之。

鄂尔多斯盆地中东部太原组碳酸盐岩烃源岩岩相类型及地球化学特征

随着鄂尔多斯盆地中东部上古生界下二叠统太原组斜道段灰岩和毛儿沟灰岩中高产气藏的发现,太原组煤系烃源岩以外的碳酸盐岩生烃潜力评价显得尤为重要。以鄂尔多斯盆地中东部地区太原组灰岩为研究对象,通过岩心观察、测井资料及地化实验数据的综合应用,分析海陆混合沉积潮坪环境中灰岩有机地化特征,并对有利于烃源岩发育的岩相类型进行划分。结果表明:①总体看来,太原组灰岩较之泥页岩有机质丰度偏低,斜道段灰岩有机质丰度最高,毛儿沟段次之;有机质类型主要以Ⅰ型为主,部分样品出现Ⅱ型干酪根特征;有机质普遍处于高成熟度演化阶段,热解峰温(T max)平均可达483℃,镜质体反射率(R o)普遍高于1.2%。②基于地球化学参数及岩石学特征的差异,将太原组灰岩共分为4类岩相类型:Ⅰ-Ⅱ型干酪根高有机质纹层状泥质泥晶灰岩相、Ⅰ-Ⅱ型干酪根中-高有机质块状泥晶灰岩相、Ⅰ-Ⅱ型干酪根中有机质块状生屑泥晶灰岩相以及Ⅰ型干酪根低有机质块状藻凝块灰岩相。③研究区中部以Ⅰ-Ⅱ型干酪根中-高有机质块状泥晶灰岩为主,烃源岩厚度不大;西部以Ⅰ-Ⅱ型干酪根中有机质块状生屑泥晶灰岩岩相为主,有效烃源岩厚度较大;东部灰岩沉积分布广且厚度大,虽以Ⅰ型干酪根低有机质块状藻凝块灰岩为主,但岩相多变,有效烃源岩厚度不小。

中西非裂谷系富油凹陷石油地质特征与勘探方向

基于地震、钻井、烃源岩测试分析等资料,对中西非裂谷系主要盆地富油凹陷石油地质特征进行研究,并探讨未来油气勘探方向。研究表明:中非裂谷系发育下白垩统湖相优质烃源岩,西非裂谷系发育上白垩统陆源海相优质烃源岩,两类烃源岩为中西非裂谷系油气富集提供了物质基础。中西非裂谷系发育包括基岩在内的多套储集层,并存在下白垩统、上白垩统和古近系3套区域盖层。晚中生代以来,受中非剪切带右旋走滑作用等地球动力学因素的影响,中西非裂谷系不同方向的盆地在裂谷作用期次、区域盖层发育层段、圈闭类型及成藏模式等方面存在差异。其中,北东—南西向盆地主要保存了早白垩世一期裂谷层序,区域盖层位于下白垩统裂陷期地层内,形成反转背斜、花状构造及基岩潜山等圈闭类型,发育“源储一体、源内成藏”及“源上储下、源下成藏”两种成藏模式;北西—南东向盆地具有多期裂谷叠置特征,发育上白垩统和古近系区域盖层,形成披覆背斜、断背斜、反向断块等圈闭类型,以“源下储上、源上成藏”为主要成藏模式。多期叠置裂谷盆地的源内成藏组合、强反转盆地的源内岩性油藏及页岩油是中西非裂谷系盆地未来勘探的重要领域。

苏北盆地古近系阜宁组二段页岩油储层岩石力学特征及其控制因素

为查明苏北盆地页岩油储层可压性特征及压后孔、缝变化规律,以古近系阜宁组二段(阜二段)为研究对象,对岩石力学特征、压裂效果及其影响因素进行研究。用计算机高分辨断层扫描成像技术(多尺度CT扫描)对岩样进行三维重构,获取孔、缝结构参数;开展地层围压下三轴力学实验,获取岩石力学参数;将压裂后的岩样按相同位置和方向再次进行多尺度CT扫描,获取压裂后三维孔、缝结构图像。根据应力-应变曲线特征,将本区页岩划分为3种类型。①1型页岩,为破裂曲线波浪下降,压后形成复杂网状缝页岩。②2型页岩,为破裂曲线类型多样,具波浪下降和垂直下降形状,压后缝网较发育的页岩。③3型页岩,为破裂曲线垂直下降,破裂后整体较完整,压后多形成纵向劈裂缝、缝网不发育的页岩。这3种类型页岩压后孔隙变化特征是:1型和2型页岩直径10~50μm孔隙占比减少,直径50~100μm孔隙增多,直径300μm以上孔隙孔容贡献增大;3型页岩压裂前、后孔径分布及孔容贡献变化不明显。研究表明,抗压强度与弹性模量、剪切模量具有正相关关系,与泊松比具有V型曲线关系;碳酸盐和黏土矿物含量是控制本区页岩力学性质的主要因素,石英和有机碳含量为次要因素。孔隙度及纹层发育特征是页岩储层可压性特征的重要影响因素。

塔里木盆地富满断控破碎体油藏储集类型特征与注水替油效果

塔里木盆地走滑断裂控制的超深油气藏是近年来中国油气勘探开发最重要领域之一,但目前该类型油藏的储集空间类型并不清楚,不同储集空间类型与注水效果关系不明确,严重制约了富满油田的高效开发。在充分分析野外露头、岩心、成像测井以及动态监测资料的基础上,系统剖析了断控破碎体的3种主要储集空间类型及其与注水效果的关系。提出了断控破碎体的概念,指出富满油田主要为断控破碎体油藏,研究结果表明:①断裂空腔型储集体主要分布在断裂带的核部,由断层滑动面产状变化引发内部体积调整形成了“空腔”型洞穴。埋藏条件下的储集空间相对较为封闭,内部孔隙空间较大,注水后原油置换率较高,部分油井动用储量的注水采收率可高达93%。②角砾间孔隙型储集体主要分布在断裂带的核部,由相邻的角砾相互支撑而形成角砾间不规则储集空间类型。该类储集体分布较为均匀,孔隙度中等,单位压降下的产液量较高,但是由于储集空间内部连接并不通畅,注水后置换率较低,需要研究探索构建立体结构井网来提高开发效果。③构造裂缝型储集体主要分布在断裂带的损伤带和过程带,在断层带的两侧和端部发育形成一定宽度的裂缝带。裂缝带周边也会发育少量孔隙,部分区域会形成一定的渗流优势通道,因此注入水的流失量较大,注水效果相对于断裂空腔型储集体较差。研究成果支撑了富满油田上产原油350×10^(4) t,可助推注水开发方案和提高采收率方案的优化,对同类型油藏高效开发具有重要的借鉴意义。