基于高温高压条件下页岩物性、三轴应力和甲烷等温吸附等针对性实验,对四川盆地及其周缘奥陶系五峰组—志留系龙马溪组深层页岩气富集特征进行研究。结果表明：①深层页岩孔隙度和水平渗透率比中浅层页岩出现较大程度的降低,含气结构以游离气为主。②深层页岩偏应力和轴向应变等参数增大,导致破裂难度增加。③受构造位置和形态、裂缝特征和流体活动期次等控制,深层页岩气保存条件更复杂。④为实现深层页岩气经济开发,深化地质认识是基础,探索针对性压裂改造工程工艺是关键。⑤Metabolograptus persculptus带—Parakidograptus acuminatus带（LM1—LM3笔石带）硅质页岩、含灰硅质页岩是深层页岩气富集高产层段和水平井穿行的有利靶窗,厚度超过10 m的焦石坝、武隆、长宁和泸州等地区是深层页岩气最有利富集区。研究指出深层页岩气勘探应优先在宽缓构造且埋深小于5 000 m、LM1—LM3笔石带页岩厚度大于10 m的“深水深层型”页岩气区进行勘探开发部署,开发工程应增加开发井水平段长度,并采用密切割、强加砂、双暂堵等工艺,以最大程度地改造深部页岩储集层。

深层页岩气是中国页岩气勘探开发的主要接替领域。四川盆地及其周缘五峰组-龙马溪组深层页岩气具有高温、高压、高地应力的地质条件，深层覆压的增加使储层的孔隙度降低15%~20%、渗透率降低90%~95%，页岩中裂隙对渗透性的贡献显著下降。不同地区五峰组-龙马溪组深层页岩含气量有一定差异，但总体上与已投入开发的中-浅层页岩差别不大，含气量主要受原始沉积条件和后期保存条件联合控制。深层页岩所经历的构造抬升剥蚀较少，保存条件相对较好。深层页岩地层温度较高，地应力较大且应力差值高，页岩塑性增强，导致裂缝起裂及延伸困难，且裂缝闭合压力高，支撑剂破碎和嵌入影响压裂支撑缝宽，裂缝导流能力递减快，长期导流能力难以维持。WF2-LM4笔石带硅质页岩生物成因石英含量高、抗压实作用强，有利于有效储层的形成和保存，由于脆性大，天然裂缝更发育，页岩气"甜窗"的底限可能超过5 km，是深层页岩气最优开发层段。深层页岩气的富集程度主要与先天沉积成岩条件的优越程度、埋藏及生-排烃历史以及后期构造抬升与变形的差异性有关。优选出具有高脆性、高孔渗性、高压力系数、高含气量等特性的深层页岩分布区，建立与深层页岩相适应的体积压裂改造技术，不断优化形成合理的生产制度，才能最大限度地采出页岩气，成功实现深层页岩气规模性有效开发。

Deep shale gas is the main alternative field for shale gas exploration and development in China. The deep shale gas in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its periphery has a geological environment of high temperature, high pressure and high crustal stress. With the increase of deep overburden pressure, the reservoir porosity is reduced by 15%-20%, the permeability by 90%-95%, and the contribution of fractures in shale to permeability is decreased significantly. The deep gas content varies in different regions in Wufeng Formation and Longmaxi Formation, but generally varies little in the middle-shallow shale that has been exploited. The gas content is mainly controlled by the original sedimentary conditions and later preservation conditions. Deep shale underwent less structural uplift and erosion, and had good oil and gas preservation conditions. Deep shale formations are characterized by high temperature, large crustal stress, and high stress difference, which can easily lead to the enhanced shale plasticity, difficulties in fracture initiation and propagation, and high closure pressure in shale. For this reason, the proppant was cracked, thus influencing the propping degree of fracturing fractures; fracture conductivity decreases rapidly, and it is difficult to maintain the long-term conductivity. The biogenic siliceous shale in the WF2-LM4 graptolite zone is characterized by high quartz content and strong resistance to compaction, which are conducive to the formation and preservation of effective reservoirs. However, due to the large brittleness and rapid development of natural fractures, the lower limit of "sweet window" of the shale may exceed 5 km, which is the optimal interval for deep shale gas development. The enrichment degree of deep shale gas is mainly related to the superior congenital sedimentary and diagenetic conditions, burial and hydrocarbon generation and expulsion history, amplitude of later uplift, and differences in structural deformation. Shale gas can be fully exploited to successfully achieve the large-scale effective development of deep shale gas by optimizing the distribution areas of deep shale with high brittleness, high porosity and permeability, high pressure coefficient and high gas conten, establishing a suitable method of volume fracturing treatment in deep shale, and a reasonable production system through continuous optimization.

在系统研究美国页岩气成藏理论和成藏条件的基础上,分析了页岩气成藏的主要控制因素,分为内部因素和外部因素:前者指页岩本身的因素,包括有机质类型和含量、成熟度、裂缝、孔隙度和渗透率、矿物组成、厚度、湿度等;后者主要包括深度、温度和压力等。其中,有机质类型和含量、成熟度、裂缝及孔隙度和渗透率是控制页岩气成藏的主要因素。结合主要影响参数,建立了预测页岩含气的种类、比例和页岩气藏发育有利区的参数模型。运用此模型类比研究发现,中国南方古生界海相页岩层中,寒武系和志留系是页岩气发育的最有利层系。寒武系页岩气藏发育最有利区位于四川盆地和米仓山—大巴山前陆以及渝东、黔北、湘西—江南隆起北缘一线;志留系页岩气藏发育最有利区位于上扬子的四川盆地和米仓山—大巴山前陆和渝东—鄂西一带、中扬子鄂北以及下扬子苏南等地。并对各有利区的泥页岩指标进行分析,以期为中国页岩气早期评价提供参考。

On the basis of the pool-forming theory and conditions for shale gas in the United States,the controlling factors for shale gas accumulation were analyzed and divided into internal and external factors.The internal control factors include the type,content and maturity of organic matters,and the fracture,porosity,permeability,mineral composition,thickness,humidity of shale.The external control factors include reservoir depth,temperature and pressure of formation.Among them,the type,content and maturity of organic matters,as well as the fracture,porosity and permeability of shale are the main factors for generating shale gas reservoir.The favorable areas for developing shale gas reservoirs were predicted by using parameter model.The analogical analysis based on the model suggests that the Cambrian system and the Silurian system are the most favorable strata for developing of shale gas reservoirs among the marine Paleozoic strata in South China.The most favorable areas of the Cambrian are located in Sichuan Basin,the Micangshan-Dabashan foreland,the northern Guizhou Province,West Hunan Province,East Chongqing and the north part of Jiangnan uplift.The most favorable areas of the Silurian are located in Sichuan Basin,the Micangshan-Dabashan foreland and East Chongqing,West Hubei Province of Upper-Yangtze River,North Hubei Province of Middle-Yangtze River and South Jiangsu Province of Lower-Yangtze River.The indexes of shale in the favorable areas were analyzed to provide reference for early evaluation of shale gas in China.

四川盆地上奥陶统五峰组—下志留统龙马溪组页岩是中国目前页岩气勘探开发的重点层系之一，已发现了涪陵、威远、长宁和昭通等页岩气藏。通过页岩气藏的详细解剖，将五峰组—龙马溪组下部龙一段页岩气富集特征概括为“高、帅、富”：“高”主要指页岩层系形成页岩气的原始物质基础条件优越，有机质类型好、丰度高、脆性矿物含量高、热演化程度适中；“帅”主要表现为构造变形较晚、变形强度较弱、变形方式与构造样式有利、抬升幅度以及现今埋深适中；“富”表现为含气量高、地层压力系数大、储层物性好、有利于储层规模改造、初始产量高、最终产出量大，开发难度相对较小，经济效益明显。优越的原始沉积条件与成岩过程（地质建造作用）与后期适度的构造变形改造与抬升剥蚀（地质改造作用）的有机组合，是页岩气的富集高产前提与关键。基于“建造”（生—储演化序列）的评价内容包括层序地层与沉积、生烃和储层孔隙形成3个方面内容，基于“改造”（储—保演化序列）的评价内容主要包括构造变形、储层裂缝形成和页岩气保存2个方面。“建造—改造”的评价思路就是沿着页岩气形成与保存的全过程，既分析页岩气形成的建造条件优劣，又评价构造改造方式、程度的正面,负面影响。基于这种评价思路所建立的各种评价要素的组合模型，更符合页岩气形成与富集规律，也能更有效地消除简单将各种要素不作区别地统一纳入评价体系所带来的偏差。

<p>Shale gas in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the Sichuan Basin is one of the key strata being explored and developed in China,where shale gas reservoirs have been found in Fuling,Weiyuan,Changning and Zhaotong.Characteristics of shale gas enrichment in the formation shown by detailed profiling and analysis are summarized as &ldquo;high,handsome and rich&rdquo;.&ldquo;High&rdquo; mainly refers to the high quality of original materials for the formation of shale with excellent key parameters,including the good type and high abundance of organic matters,high content of brittle minerals and moderate thermal evolution.&ldquo;Handsome&rdquo; means late and weak deformation,favorable deformation mode and structure,and appropriate uplift and current burial depth.&ldquo;Rich&rdquo; includes high gas content,high formation pressure coefficient,good reservoir property,favorable reservoir scale transformation and high initial and final output,with relative ease of development and obvious economic benefit.For shale gas enrichment and high yield,it is important that the combination of shale was deposited and formed in excellent conditions (geological construction),and then underwent appropriate tectonic deformation,uplift,and erosion (geological transformation).Evaluation based on geological construction (evolution sequence from formation to the reservoir) includes sequence stratigraphy and sediment,hydrocarbon generation and formation of reservoir pores.Based on geological transformation (evolution sequence from the reservoir to preservation),the strata should be evaluated for structural deformation,the formation of reservoir fracture and preservation of shale gas.The evaluation of the &ldquo;construction-transformation&rdquo; sequence is to cover the whole process of shale gas formation and preservation.This way,both positive and negative effects of the formation-transformation sequence on shale gas are assessed.The evaluation models based on this strategy would be more accurate,reliable and would avoid bias derived from indiscriminate and simplistic use of all parameters in the models.</p>

Overpressured shale gas plays have been found in the Lower Paleozoic marine shales of Jiaoshiba region in the Sichuan basin, China. The black shales from the Upper Ordovician Wufeng Group (O(3)w) and the lower part of Lower Silurian Longmaxi Group (Sil) are the producing reservoirs. Overpressure is widespread in the O(3)w-S(1)l shales with the pressure coefficient up to 1.74. Fluid inclusion microthermometric and Raman spectroscopic techniques, PVT and basin modeling are used to investigate overpressure generation and evolution in the O(3)w S(1)l shales. The results show that thermocatalytic dry gas generation is the main genetic mechanism for overpressure development in the O(3)w-S1l shales with specific characteristics as follows: (1) the maximum burial depth of overpressured shales is more than 6200 m without anomalously low density and high primary porosity according to wireline log and core data; (2) the over-mature O(3)w-S(1)l shales with the mean TOC values ranging from 3.36 wt% to 4.48 wt% and the vitrinite reflectance values of 2.7%-2.9% Ro determined by kerogen FTIR (Fourier transform infrared spectroscopy) characteristics, has excellent potential to produce dry gas; (3) overpressured reservoirs are characterized by high gas saturations, and the pressure coefficients positively correlate with gas saturation; (4) the abnormally high pressures recorded in the fluid inclusions are coincident with high homogenization temperatures, which is supportive of overpressure occurring during dry gas generation and provides convincing in-situ evidence for gas generation overpressuring. The calculated pore-fluid pressures for methane inclusions within the maximum buried O(3)w-S(1)l shales are approximately 90.3-139.4 MPa, suggesting that gas generation produced a maximum pressure gradient of 23.1 MPa/km, which is equivalent to the litho static magnitudes. The overpressure evolution in the O(3)w-S1l shales is noticed to have evolved through four stages: a rapidly increasing overpressure caused by thermocatalytic gas generation ( > 145-85 Ma), a rapid pressure release (85-61Ma), overpressure preservation (61-20 Ma), and a relatively slow pressure release (20 Ma - present). During post-generation evolution (85 Ma- present) of the O(3)w-S(1)l shales, both the overpressure and pressure coefficients decreased with time due to the intensive tectonic uplifts and denudation, and approximately 19.00/0-28.5% of the initial total gas content was continuously released until the present-day overpressure state. The study of overpressure evolution in the O(3)w-S51 shales provides basic information for the further study of the conversion between adsorbed gas and free gas, and the method and technique used in this study to stress the overpressure generation and evolution may be generally applied to other overpressured or normally pressured shale gas systems.

四川盆地南部地区(简称&#x0201c;川南地区&#x0201d;)海相页岩气资源潜力巨大,目前埋深2 000~3 500 m的中浅层优质页岩气资源已实现有效开发,埋深3 500~4 500 m的深层页岩气也取得了战略突破。通过系统总结川南地区下志留统龙马溪组页岩气勘探地质认识,重点分析了川南地区页岩气高产的关键因素,提出了下一步的勘探方向。研究表明:①海相陆棚沉积环境水体相对深度控制储集层发育和分布。深水陆棚的相对深水区发育&#x02160;类储集层且连续厚度更大。海相陆棚沉积环境水体相对深度可以用氧化还原条件来确定,铀、钍质量比大于1.25时为缺氧还原环境,水体为相对深水区。铀、钍质量比为0.75~1.25时为弱还原弱氧化环境半深水;铀、钍质量比小于0.75时为强氧化环境相对浅水。②页岩储集层压裂改造支撑缝高一般为10~12 m,若&#x02160;类储集层连续厚度大于10 m,支撑段则均为优质储量,钻遇&#x02160;类储集层连续厚度越长,产量越高。③川南地区3 500~4 500 m深层页岩气具有地层压力大、压力系数高、孔隙保存好、孔隙结构优以及游离气占比大的特征,是页岩气勘探最有利的新领域,压力系数大于1.2是页岩气井获得高产的必要条件。④深层页岩气建产区高产井模式为龙一₁¹&#x02014;龙一₁³小层厚度大于10 m区域,水平段长1 500 m,&#x02160;类储集层钻遇率超过90%,应采用密切割+高强度加砂+大排量+大液量的主体工艺技术。⑤深水陆棚内相对深水区与3 500~4 500 m埋深区域在川南地区表现出较好的重合,重叠区域是今后川南地区页岩气最有利的勘探开发区带。通过理论技术进步,川南地区页岩气有望实现年产450&#x000D7;10⁸m³的目标。图16表5参32

高过成熟海相页岩有机质炭化点（区）的分布规律和主控因素是页岩气勘探面临的重要课题。围绕四川盆地及其周缘下寒武统和下志留统页岩分布区，以重点炭化区精细解剖为基础，开展了2套页岩有机质炭化区精细预测和热成熟度区域编图，探索海相页岩有机质炭化区分布规律和主控因素。研究认为：①在下志留统页岩分布区，存在川东—鄂西、鄂西北部、川南西部和仁怀—渝西南4个有机质炭化区，面积近40 000 km²，其中川南西部炭化区主体位于峨眉玄武岩分布区。②在下寒武统页岩分布区，有机质炭化区面积占比超过80%，非炭化区仅分布于威远—资阳、磨溪—高石梯、长阳和瓮安—镇远等4个区块，面积约为62 600 km²。③峨眉火成岩省为晚二叠世的极热事件，使得川南西部下志留统和下寒武统页岩热成熟度R_O值分别增加0.2%~0.4%和0.2%~1.0%。马边—峨边位于峨眉玄武岩厚度高值区，也是下寒武统和下志留统页岩有机质炭化程度最严重区域。④下寒武统和下志留统页岩有机质炭化的主控因素既有相似之处，也存在一定差异。前者主控因素为长期的深埋背景，晚二叠世的极热事件仅使局部地区炭化程度更趋严重。后者主控因素相对复杂，在仁怀—渝西南、川东—鄂西、鄂西北3个地区受深埋背景控制，在川南西部则受深埋背景和晚二叠世的高地温作用双重控制。

The distribution and main controlling factors of organic matter carbonization points （zones） of over-mature marine shale are important issues for shale gas exploration. This paper focuses on the Lower Cambrian and Lower Silurian shale in the Sichuan Basin and its periphery. Based on the detailed anatomy of key carbonization areas， predictions of shale organic matter carbonization areas and regional mapping of thermal maturity are carried out to explore and reveal the distribution and main controlling factors of the carbonization zones of organic matter in the two sets of shales.Four preliminary conclusions were obtained：（1）In the Lower Silurian shale distribution area，there are four organic matter carbonization zones，namely，eastern Sichuan-western Hubei， nor-thwestern Hubei，southern Sichuan and Renhuai-southwestern Chongqing，covering an area of nearly 40 000 km²，of which the main part of the western carbonization zone in southern Sichuan is located in the Emei basalt distribution area. （2）In the Lower Cambrian shale distribution area， the organic carbonization area accounts for more than 80%. The non-carbonization area is only distributed in Weiyuan-Ziyang， Moxi-Gaoshiti， Changyang and Weng'an-Zhenyuan with an area of about 62 600 km². （3）The Emei igneous rock event was an extreme heat event in the Late Permian， which increased the thermal maturity R_O value of the Lower Silurian and Lower Cambrian shale in the western part of southern Sichuan by 0.2%-0.4% and 0.2%-1.0%， respectively. Mabian-Ebian is located in the high-value area of the Emei basalt thickness， and is also the area with the highest degree of carbonization of organic matter in the Lower Cambrian and Lower Silurian shale. （4）The main controlling factors of organic matter carbonization of the Lower Cambrian and Lower Silurian shale have similarities and differences. The main controlling factor of the former is the long-term deep burial background， and the extremely thermal event in the Late Permian only made the degree of carbonization in some areas more serious.The latter’s main controlling factors are relatively complex， and are controlled by deep burial background in the three regions of Renhuai-southwestern Chongqing， eastern Sichuan-western Hubei， and northwestern Hubei. In western Sichuan， it was controlled by deep burial background and high ground temperature in Late Permian.

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 °C 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.

Marine shales in South China, such as the Upper Ordovician Wufeng (O(3)w) and Lower Silurian Longmaxi (S(1)l) shales, have generally experienced a long-term burial and rapid uplift process. The variations of temperature and pressure caused by the complex tectonic movements have significant effects on the shale gas storage capacities. Based on the supercritical Dubinin-Radushkevich (SDR) equation and high-pressure methane (CH4) adsorption experiments, equations to calculate the shale gas storage capacities under geological conditions were established in this work. Using the derived equations, the gas storage capacities in two basic geological processes were modeled, namely, the burial process, which has an increased gas content, and the uplift process, which has a constant gas content. The two basic models were applied to investigate the evolution of the shale gas content of the O(3)w-S1(l) shales in the JY 1 Well in the Fuling shale gas field, Sichuan Basin, South China. Geological models of the gas storage capacities of the shales during burial show that the storage capacity of adsorbed gas (SCadsorbed (gas)) initially rapidly increases and then slowly decreases with the increasing burial depth. The storage capacities of free gas (SCfree gas) and total gas (SCtotal gas) increase with the increasing burial depth. Compared with SCadsorbed gas, SC(free gas )significantly increases as the pore pressure increases. Such an obvious difference implies that free gas is the predominant gas form in the initial stage of shale gas production. During uplift, the gas content remains unchanged, resulting in a linear decrease in SCfree gas and a linear increase in SCtotal gas. Nonetheless, SCfree gas during uplift is still higher than SC(free gas )during burial at the same burial depth. The modeling of the shale gas content evolution of the O(3)w-S(1)l shales in the JY 1 shows that from the maximum burial depth of 6200 m to the present-day burial depth of 2415 m, the free gas content declines by 0.89 m(3)/t, from 2.30 m(3)/t to 1.41 m(3)/t, while the adsorbed gas content only increases by 0.58 m(3)/t, from 0.47 m(3)/t to 1.05 m(3)/t. This difference indicates that only a small amount (0.31 m 3 /t) of shale gas was lost during the uplift and that most (0.58 m(3)/t) of the reduced free gas was converted into adsorbed gas. A unique aspect of this study is that we illustrate how adsorbed and free gas are converted when the total gas content remains constant. Moreover, the two basic geological models established in this study can also be applied to other shale gas systems with complex tectonic movements.

基于涪陵、威远、长宁、泸州、渝东南等地区海相页岩气勘探开发实践,结合实验测试分析,总结中国南方海相页岩气差异富集的6个特征：①有机质丰度越高、演化程度越适宜,吸附气量和总含气量越高;②干酪根热解和液态烃裂解联合供气是海相页岩气的主要来源;③富有机质页岩比表面积和孔体积随演化程度增加表现出先增加后减小的特征,当有机碳含量为2.23%~3.33%时,储集层以油润湿为主,最有利于页岩气富集;④顶、底板厚度越大,页岩气含量越高,末次构造抬升时间越长、抬升幅度越大,页岩气散失量越大;⑤地层埋深与倾角对不同构造部位的控气耦合作用不同,存在两种页岩气差异富集演化模式;⑥生-储-保有效综合匹配决定了成藏品质,有效生气量和时段、适度孔隙演化、良好保存条件在时空的良好匹配是页岩气富集的一种重要配伍。图14表1参37

四川盆地东南缘（川东南）丁山构造五峰组—龙马溪组页岩气勘探已取得突破，但相比涪陵页岩气田焦石坝构造，其富集高产因素又体现出其自身的特殊性。以四川盆地丁山和焦石坝地区五峰组—龙马溪组为研究对象，综合利用钻井、测井、地震及分析化验等资料，明确了两地区主要富集条件的差异性，建立了2种目标类型页岩气成藏富集模式，研究发现：（1）丁山优质页岩层段TOC≥3%的页岩仅发育于五峰组—龙马溪组一段①—③层，厚15~19 m，明显比焦石坝薄（焦页1井近38 m）；（2）丁山构造保存条件明显受齐岳山断裂控制，平面上远离齐岳山断裂、埋深更大的斜坡带和深埋平缓带页岩气层压力系数、孔隙度和含气量明显增大，而焦石坝构造保存条件明显受周边控制构造的断裂影响，压力系数、孔隙度和含气量仅在断裂附近出现明显的降低；（3）丁山优质页岩层段在自身脆性方面与焦石坝无明显差异，但由于埋深变化较大，埋深处于3 500~4 500 m富集区的优质页岩层段的地应力、岩石破裂压力明显增大。研究认为沉积环境造成了两地区页岩原生品质具有一定的差异，其中丁山属于“较快速海退型”陆棚相沉积，而焦石坝属于“缓慢海退型”陆棚相沉积；而控制构造的断裂是造成页岩气逸散方式和程度不同的主要因素。根据以上特点，建立了丁山 “齐岳山断裂带主体控制、浅埋藏区垂向、横向联合逸散、深埋藏区富集”的盆缘“鼻状断背斜富集型”、焦石坝盆内“控边断裂垂向逸散为主、横向逸散微弱、主体稳定区富集”的“断背斜富集型”成藏富集模式。

A breakthrough in Wufeng-Longmaxi shale gas exploration has been made in Dingshan tectonic area in the southeastern margin of Sichuan Basin, however, compared with the Jiaoshiba structure in Fuling shale gas field, its enrichment and high yield factors reflect its own particularity. Therefore, this paper takes Dingshan and Jiaoshiba Wufeng-Longmaxi formations in Sichuan Basin as the research object. Through the comprehensive use of drilling, logging, seismic and laboratory data, the differences of the main enrichment conditions in the two regions are identified, and two types of shale gas accumulation and enrichment models are established. The results show that: (1) For the Dingshan high-quality shale, the layer with TOC≥3% is only developed in the ①-③ layers of the first segment of Wufeng-Longmaxi formations, with a thickness of 15-19 m, which is significantly thinner than that of Jiaoshiba area (nearly 38 m of Well JY1); (2) The preservation conditions of the Dingshan structure are obviously controlled by the Qiyueshan fault, and the pressure coefficient, porosity and gas content of the shale gas layer increase significantly in the area far away from the Qiyueshan fault, deeper buried slope zone and in the deep buried gentle zone. However, the preservation condition of Jiaoshiba structure is obviously affected by the fault of the surrounding control structure, and the pressure coefficient, porosity and gas content are only significantly reduced near the fault; (3) There is no significant difference in brittleness between the high quality shale segment in Dingshan and that in Jiaoshiba. However, due to the large change of burial depth in Dingshan area, the in-situ stress and rock fracture pressure of the high quality shale segment with burial depth of 3 500-4 500 m increase obviously. The study shows that the sedimentary environment has caused some differences in the primary shale quality between the two regions. Dingshan area is “relatively rapid regressive” continental shelf facies, and Jiaoshiba area belongs to “slow regression type” continental shelf facies. The fault, which controls the structure characteristics, is the main factor that causes the different way and degree of shale gas escape. According to the above characteristics, the “nosed fault-anticline enrichment” accumulation model in basin margin of “Qiyueshan fault zone main body control, shallow burial zone vertical and horizontal joint escape, enrichment in deep buried areas” is established in the Dingshan area, and the accumulation model of “fault-anticline enrichment” in Jiaoshiba area of internal Sichuan basin is characterized by “vertical dispersion of the control edge fault is dominant, the transverse dispersion is weak and the main stable region is enriched”.

常压页岩气藏的压力系数和含气量较低,地层能量较弱,具有中&mdash;低丰度、中&mdash;低品位、资源总量大和储量规模大等特征。中国南方常压页岩气藏分布广泛,具有良好的地质背景与富集条件,但其类型、形成机制和富集规律不明。基于页岩气勘探开发实践和地质解剖,探讨了四川盆地及其周缘五峰组&mdash;龙马溪组常压页岩气藏的类型、形成机制、分布特征和富集规律,提出了常压页岩气藏勘探开发的前景与技术对策。研究认为,常压页岩气藏主要包括优质页岩缺失/减薄型、早期逸散型、断裂破坏型和残留向斜型4种类型。常压页岩气藏的分布与富集明显受构造作用控制。通过对常压页岩气藏的类型、特征和形成机制等综合分析,认为残留向斜型常压页岩气藏为目前最有利的勘探开发类型。地质评价中应聚焦在靠近盆地、抬升时间晚、残留向斜面积大、远离深&mdash;大断裂且裂缝封闭时间早的地区开展研究,优选靠近向斜核部、构造稳定、相对高压力系数和埋深适中的区域开展页岩气勘探开发。技术对策上,建议钻井上采用低泥浆密度钻井液,压裂上采取少段多簇、大排量、中等液量和高砂量,以此来实现经济有效的体积改造。该研究成果将为常压页岩气的地质评价和勘探实践提供参考。

Normal pressure shale gas reservoirs have low pressure coefficient and gas content as well as small stratum energy, characterized by mid-low abundance, mid-low grade, large amount of resource and large scale of reserves. Normal pressure shale gas reservoirs are widely distributed in South China with favorable geological settings and accumulation conditions, but their types, formation mechanism and enrichment regularities are still unknown. According to the shale gas exploration and development practice as well as geological analyses, this study explores the types, formation mechanism, distribution characteristics and enrichment laws of normal pressure shale gas reservoir, and proposes the exploration prospect and technical strategies of normal pressure shale gas reservoirs. This research suggests that there are four main types of normal pressure shale gas reservoirs, i.e., absent/thinning type of high-quality shales, early escaping type, fault failure type and residual syncline type. The distribution and enrichment of normal pressure shale gas reservoirs are obviously controlled by geological tectonism. Through comprehensively analyzing the types, formation mechanism and features of normal pressure shale gas reservoirs, it is suggested that the residual syncline type is the most favorable exploration target. Geological evaluation should focus on the areas close to basin, far from regional deep fault, showing late uplift, large area of residual syncline, and early sealing of fractures. The exploration and development target should preferentially be adjacent to the center of syncline with stable structure, high pressure coefficient and moderate burial depth. As for technical countermeasures, it is recommended to use the drilling fluid with low mud density and the fracturing with small number of segments and multi-perforation clusters, large displacement, medium liquid volume and high sand volume to achieve cost-effective volume transformation. The research results can provide a reference for the geological evaluation and exploration practice of normal pressure shale gas reservoirs.

The Wufeng and Longmaxi organic-rich shales host the largest shale gas plays in China. This study examined the petrography, rare earth element (REE) and other trace-element geochemistry, Sm-Nd geochronology, and isotope geochemistry (87Sr/86Sr, δ18O, δ13C) of fracture-cementing minerals within core samples of the Wufeng and Longmaxi Formations from the Jiaoshiba shale gas field in order to (1) characterize the mineral phases occurring in the veins (mineralized fractures); (2) determine the ages of the calcite by the Sm-Nd isochron dating method; (3) understand the sources of calcite-precipitating fluids; and (4) explore the possible mechanisms responsible for calcite vein formation in shale gas systems. The fractures hosted in the Longmaxi Formation are mineralized with quartz as the predominant fracture cement, and calcite as an intracementation phase postdating the earlier quartz cement. In contrast, the fractures hosted in the Wufeng Formation are dominantly mineralized by calcite, which occurs either as the only cement present or as a cement phase predating later quartz cement. Calcite veins within the Longmaxi Formation have a Sm-Nd isochron age of 160 ± 13 Ma and δ13C values of –4.71‰ to –3.11‰, δ18O values of 17.1‰–17.4‰, and 87Sr/86Sr values of 0.72437–0.72869. Calcite veins within the Wufeng Formation yielded a Sm-Nd isochron age of 133 ± 15 Ma and are characterized by δ13C values of –2.29‰ to –1.03‰, δ18O values of 17.3‰–17.7‰, and 87Sr/86Sr values of 0.72202–0.72648. The similarity between 87Sr/86Sr values of the calcite and those of their respective surrounding host rocks (0.72670–0.72875 of the Longmaxi shales; 0.72030–0.72648 of the Wufeng shales), combined with relatively depleted δ13C and uniform fluid δ18O isotopic features, indicates that the calcite-precipitating fluids within the Wufeng and Longmaxi Formations were derived largely from their respective surrounding host-rock sources. REE data equally indicate that the distinguishable Eu anomalies (6.20–19.35; 4.45–11.91), Y anomalies (1.03–1.50; 1.44–1.70), and Y/Ho ratios (28.80–39.16; 38.86–45.18) of calcite veins within the Longmaxi and Wufeng Formations were controlled by their respective surrounding host rocks. The Sm-Nd isochron ages and fluid inclusion data of fracture cements suggest that fracture opening and calcite precipitation in composite veins within the Wufeng and Longmaxi Formations were triggered by gas generation overpressurization.

中国的海相富有机质页岩经历了多期构造改造，其含气性具有明显的差异。页岩气在不同构造演化阶段的保存条件是揭示页岩气差异富集机理的关键科学问题之一，开展构造-热演化研究可以明确其热演化史和构造隆升-剥蚀过程，为其评价提供演化格架。研究以丁山地区下古生界页岩为对象，联合磷灰石裂变径迹、磷灰石（U-Th）/He和锆石（U-Th）/He等多个古温标反演热演化史，结合镜质体反射率重建的最高古地温剖面，对丁山地区燕山期以来的差异构造隆升过程和剥蚀量进行了恢复，并在此基础上结合流体包裹体分析对丁山地区龙马溪组页岩的压力演化过程进行了模拟；根据页岩在埋藏&mdash;抬升过程中的温、压演化特征，定量表征了不同抬升阶段页岩含气量的变化，建立了龙马溪组页岩&quot;埋藏&mdash;生烃&mdash;抬升&quot;的演化格架。分析表明，丁山地区在燕山期和喜马拉雅期经历了不同的构造隆升过程。燕山期表现为&quot;早期快速隆升&mdash;晚期缓慢隆升&quot;的分段隆升，具有自NW向SE递进隆升且隆升幅度逐渐增大的特征；喜马拉雅期表现为整体快速隆升。燕山期是丁山地区产生差异构造隆升的主要时期。受这种差异构造隆升-剥蚀作用的影响，龙马溪组页岩的降温、降压过程和页岩气的散失过程具有明显的差异。燕山期的差异构造隆升是造成丁山地区龙马溪组页岩含气性呈平面分带的主要原因。

China's marine organic-rich shale has undergone multiple periods of tectonic reworking, and its gas-bearing properties have obvious differences. The preservation condition of shale gas in different stages of tectonic evolution is one of the key scientific issues to reveal the differential enrichment mechanism of shale gas. The studies on tectono-thermal evolution can clarify its thermal evolution history and tectonic uplift-denudation process, providing an evolutionary framework for its evaluation. Using the geothermometers such as apatite fission track, apatite (U-Th)/He and zircon (U-Th)/He, this study conducts the thermal evolution history inversion of the Lower Paleozoic shale in Dingshan area. In combination with the highest geothermal profile reconstructed by vitrinite reflectivity, it restores the differential tectonic uplift process and denudation thickness since the Yanshanian in Dingshan area. In combination with fluid inclusion analysis, it simulates the pressure evolution of the Longmaxi Formation shale in Dingshan area. According to the evolution characteristics of temperature and pressure of the shale in the process of burial-uplift, this paper quantitatively characterizes the variation of shale gas content in different uplifting stages, and establishes the evolutionary framework for "burial-hydrocarbon generation-uplift" of the Longmaxi Formation shale. The analysis shows that Dingshan area underwent different tectonic uplift processes during Yanshanian and Himalayan periods. The uplift process showed periodicity characterized by "rapid uplift in early stage but slow uplift in late stage" with progressive uplift from NW to SE and gradually increasing magnitude of exhumation during Yanshanian period, but overall rapid uplift during Himalayan period. The Yanshanian period is the main period of differential tectonic uplift in Dingshan area. Under the influence of the differential tectonic uplift and denudation, the cooling and pressure reduction process and the shale gas loss process in the Longmaxi Formation shale are significantly different. The differential tectonic uplift in Yanshanian period is the main reason for the gas-bearing zonation of the Longmaxi Formation shale in Dingshan area.

Significant heterogeneity in deep shale gas enrichment is observed within the Wufeng-Longmaxi formations in southeastern Sichuan, yet the dynamic evolution processes and mechanisms driving differential enrichment remain unclear. This study focuses on the complex marginal structural belt (Dongxi, Dingshan, Xinchang) and the steep intra-basin structural belt (Shilongxia, Lizi), and investigates the mechanisms of deep shale gas enrichment based on analyses of vein types, carbon and oxygen isotopes, rare earth elements, and fluid inclusion homogenization temperatures, integrated with basin modeling. The results show that: (1) Vein characteristics reflect differences in gas preservation conditions. Fracture-filling veins are mainly composed of calcite and quartz, formed during the Late Cretaceous to Miocene (10-95 Ma). In the intra-basin high-steep anticlines, veins are associated with hydrothermal and meteoric water origins, and exhibit wide homogenization temperature ranges and three phases of fluid activity, indicating poor gas preservation. In contrast, the marginal zones are dominated by veins derived from in situ formation fluids, show narrower homogenization temperature ranges, and experienced fewer fluid events (1–2 phases), suggesting favorable preservation conditions. (2) Fracture-fluid interactions dominate reservoir evolution. At maximum burial depth, deep shale reservoirs in the Wufeng-Longmaxi formations were strongly overpressured (pressure coefficient >2.0) and had high gas contents (>6 m³/t). In the intra-basin high-steep structures, repeated opening and closure of high-angle fractures during the Yanshanian–Himalayan uplift led to rapid gas loss from the Late Cretaceous to Oligocene, resulting in present-day gas content below 2 m3/t, whereas marginal fault-bend anticlines with weak high-angle fracture development retained overpressure (pressure coefficient > 1.8), and current gas contents remain above 6 m3/t. (3) Structural style controls differential enrichment. In areas of structural superposition between the Luzhou paleo-uplift and the southern Sichuan finger-like structures (Lizi, Shilongxia), significant stratigraphic shortening and the development of back-thrust and strike-slip faults led to severe reservoir damage. In contrast, marginal fault-bend anticlines experienced less shortening and weaker deformation; regions without back-thrust faults retained higher gas contents. Favorable enrichment zones are identified in fault-bend anticlines without back-thrusts and in slope or syncline areas far from high-steep or strike-slip fault zones. These findings provide theoretical support for targeted exploration and efficient development of deep shale gas resources in the Sichuan Basin.

Quartz is an important mineral component in the Late Ordovician – Early Silurian Wufeng-Longmaxi Formation with various forms and sources and has a significant impact on the properties of shale gas reservoirs. In this study, geochemical analysis, scanning electron microscopy (SEM) observation, and rock mechanics testing were performed on shale samples from the Wufeng-Longmaxi Formation in north-western Hunan, South China. Quartz is classified into four types based on morphological features and cathodoluminescence (CL) images under SEM – terrigenous detrital quartz, quartz overgrowths, biogenic skeletal quartz and microquartz. The quartz in Upper Longmaxi Formation is predominantly of terrigenous origin and contains a small amount of quartz formed by clay transformation. The quartz in the Wufeng-Lower Longmaxi Formation is predominantly biogenic. The biogenic quartz has a direct effect on organic matter (OM) abundance, pore structure and brittleness. It is indicated by the positive correlation with TOC content and biogenic Ba content that biogenic quartz-rich strata have high paleoproductivity. The rigid frameworks formed by biogenic quartz during the early diagenesis stage facilitated the preservation of the primary pores. The interparticle pores of biogenic quartz are the space for OM preservation and migration, creating conditions for the development of OM pores. Additionally, the calculated brittleness index (BI) shows a positive correlation with biogenic quartz content, indicating that layers rich in biogenic quartz are more conducive to fracture. Therefore, the Wufeng-Lower Longmaxi Formation has higher OM content, porosity and represents a more favorable exploration and development target.

中美页岩气地质和地表条件的对比分析表明，中国南方海相页岩与北美典型页岩的主要评价指标相近，是页岩气勘探的主攻层系。其中，四川盆地及周缘地区是有利勘探地区。中国石油、化工股份有限公司2006年以来，经历6年的研究与勘探探索，2012年在四川盆地涪陵焦石坝地区龙马溪组页岩气获得重大突破，发现了涪陵页岩气田，取得了中国页岩气的首个商业发现。五峰组龙马溪组页岩气富集与高产的地质因素包括原始沉积条件和后期保存条件，台内坳陷控制优质页岩的形成分布，页岩厚度大、有机质含量高是页岩气选区的首要评价指标。保存条件影响页岩气的富集程度，四川盆地内部总体保存条件较好，有三叠系膏盐岩分布的地区保存条件好，页岩气层段压力系数高，页岩气富集程度高。在选区评价中，原始沉积条件和后期保存条件均有利的地区是页岩气勘探的有利区。通过对典型探井五峰组龙马溪组页岩气富集条件的分析表明，有机质提供了页岩气富集的物质基础，有机质孔是页岩气富集的主要储集空间，层理(缝)是页岩气水平渗流的高效通道，高硅质含量具有良好的可压性，高压力系数指示页岩气富集程度高。有机质、有机质孔、层理(缝)、硅质含量和压力系数等表征页岩气富集与高产的5种关键参数具有成因联系和统计相关的特征，纵向上又具有&ldquo;五性一体&rdquo;的分布特征，从而决定了五峰组龙马溪组下部富含有机质的优质页岩层段既可以富集页岩气，又有利于页岩气的开发，是开发页岩气的主要层段和水平井轨迹的关键目标层。

根据页岩气地质理论研究进展和勘探发现,基于&quot;源-盖控烃&quot;论分析了四川盆地及其周缘上奥陶统五峰组-下志留统龙马溪组页岩气富集的主控因素。①&quot;源控&quot;主要表现在优质页岩厚度、面积、有机碳含量等物质基础参数控制了页岩的生烃能力和储集能力,上奥陶统五峰组-下志留统龙马溪组一段下部页岩(WF2-LM4笔石页岩段)具有沉积速率低、有机质类型好、有机碳含量高和生烃能力强等特点,具备良好的页岩气发育生烃物质基础;浮游藻类来源的成烃生物有利于大量生烃和有机质孔大量发育,且高有机碳含量保证了发育大量有机质孔并形成三维连通的有机质孔孔隙网络,为天然气提供良好的赋存空间和渗流通道。②&quot;盖控&quot;的盖层包括直接盖层和间接盖层,直接盖层指龙马溪组一段中上部(LM5笔石页岩段及其以上)页岩对五峰组和龙马溪组一段下部页岩(WF2-LM4笔石页岩段)的封闭;中下三叠统膏盐岩、泥岩间接盖层(区域盖层)保证了一定的压力封闭,使得其下的五峰组和龙马溪组页岩气能有效富集,形成高压富集的页岩气藏(焦石坝、富顺-永川、长宁等地区);在中下三叠统缺失的地区,先存的高压封闭体系被破坏,页岩气保存失去有效性,形成低压-常压富集的页岩气藏(渝东南彭水、云南昭通等地区)。源-盖空间匹配关系的数量(静态匹配)和质量(动态匹配)控制着页岩气富集位置和富集程度。四川盆地及其周缘上奥陶统五峰组-下志留统龙马溪组一段下部页岩(WF2-LM4笔石页岩段)发育厚度大,中下三叠统膏盐岩、泥岩盖层发育,主成藏期在J₃-K₁以新的地区,是四川盆地及其周缘上奥陶统五峰组-下志留统龙马溪组页岩气富集的有利地区。

Based on the exploration discoveries of shale gas and research progresses of relevant geological theory as well as "source-cap controlling hydrocarbon" theory, the main controlling factors of shale gas enrichment in Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation of Sichuan Basin and its periphery were analyzed:(1) "Source control" means that the shale hydrocarbon generation and reserving capacity can be controlled by the thickness, area, total organic carbon content of high-quality shale and other basic factors. The shale in Upper Ordovician Wufeng Formation-Lower Member 1 of Lower Silurian Longmaxi Formation (WF2-LM4 graptolite shale member) is characterized by slow sedimentary rate, good type of organic matter, high total organic carbon content and great hydrocarbon generation capacity, thus providing a favorable hydrocarbon-generation material basis for shale gas development; the hydrocarbon-generation materials such as planktonic algae are beneficial for massive hydrocarbon generation and organic matter development, and high organic carbon content is able to ensure the development of massive organic-matter pores, so as to form a three-dimensional connected network of organic-matter pores and provide favorable occurrence space and flow channel for natural gas. (2) In terms of "cap control" theory, the cap can be divided into direct cap and indirect cap. Direct cap refers to the confining bed between the shale in mid-upper Member 1 of Longmaxi Formation (LM5 graptolite shale member and above) and that in Wufeng Formation and the lower Member 1 of Longmaxi Formation (WF2-LM4 graptolite shale member). Indirect cap (regional cap) in the Mid-Lower Triassic gypsum rocks and mudstones can guarantee the pressure sealing to a certain degree. As a result, the shale in Wufeng Formation and Longmaxi Formation can be effectively enriched to form high-pressure enriched shale gas reservoirs (Jiaoshiba, Fushun-Yongchuan and Changning, etc.). In the regions with absent Mid-Lower Triassic, the pre-existing high-pressure closed system was destroyed and the shale gas preservation availability was lost, thus forming the shale gas reservoirs enriched under low-normal pressure (Pengshui in southeastern Chongqing, Zhaotong in Yunnan, etc.) The enrichment location and degree of shale gas is controlled by the quantity (static match) and quality (dynamic match) of source-cap spatial match relationship. Research results indicate that the shale in Upper Ordovician Wufeng Formation-lower Member 1 of Lower Silurian Longmaxi Formation of Sichuan Basin and its periphery (WF2-LM4 graptolite shale member) is developed with a large thickness, together with Mid-Lower Triassic gypsum rocks and mudstones. The regions with the main reservoir accumulation period of J₃-K₁ or after J₃-K₁ are favorable areas for shale gas enrichment in Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation of Sichuan Basin and its periphery.

Ground-breaking discoveries in the Cambrian Qiongzhusi Formation of the Sichuan Basin have unveiled one of the world’s geologically oldest shale gas play. An integrated analysis of lithofacies, sedimentology, reservoir properties, thermal maturity, and hydrocarbon generation-expulsion history indicates that most productive shale gas reservoirs are predominantly located around the paleouplifts of the Yangtze craton, where equivalent vitrinite reflectance (EqVRo) values are below 3.5%. During the early Cambrian, deep-water depositional environments dominated the Yangtze craton, leading to the widespread accumulation of black shale (20–80 m thick) across the central Sichuan Basin, Huangling, and central Guizhou regions. Unlike other cratonic regions, these areas later evolved into paleouplifts, resulting in relatively shallow burial depths and lower present-day thermal maturity (EqVRo &amp;lt; 3.5%). As a result, the black shales adjacent to these paleouplifts have limited oil generation and expulsion, thereby preserving higher porosity and enhanced shale gas potential. Two distinct reservoir types have been identified: organic-rich shale (total organic carbon content &amp;gt;2%) and organic-poor silty shale (total organic carbon &amp;lt;0.5%). The organic-rich shale includes the deeply buried, overpressured Qiongzhusi shale within the Deyang-Anyue intracratonic rift trough in the central Sichuan Basin, and the normally pressured Niutitang shale outside the Sichuan Basin which is buried in shallower depth. In comparison, the organic-poor silty shale is overpressured and occurs along the Deyang-Anyue rift trough slopes. In conclusion, overpressured Cambrian shale gas reservoirs with EqVRo &amp;lt; 3.5% represent the most prospective exploration targets in the Sichuan Basin, offering valuable insights for global Cambrian shale gas exploration.

根据烃源岩演化过程中残留生烃母质变化原理,建立了TOC恢复的数学地质模型,提出了TOC演化与各种主控因素之间的定量关系模式,通过对模式中各主控因素在自然条件下变化的特征取值,计算得到了TOC恢复系数,做出了泥质岩烃源岩和碳酸盐岩烃源岩在含不同类型干酪根情况下的TOC演化图版。这一方法的最大特色是避免了人为主观因素和高温压物理模拟实验条件可能带来的结果偏差。研究表明:随着热演化程度的增加,烃源岩内残留的TOC含量逐渐减少,在大量生排烃阶段(R_O=0.5％～2.0%)变化幅度最大;处于高过成熟阶段(R_O&gt;1.2%)的烃源岩,其原始TOC恢复系数随R_O增大而逐渐增加,含Ⅰ型、Ⅱ型、Ⅲ型母质的泥质岩烃源岩TOC恢复系数分别可达3.0、2.0、1.4;含Ⅰ型、Ⅱ型、Ⅲ型母质的碳酸盐岩烃源岩TOC恢复系数分别可达3.2、2.2、1.5。论文例举了源岩TOC恢复在实际工程中的应用。

According to the change of residual hydrocarbon generation materials in the evolution process of source rocks,the geological conceptual model about the <i>TOC</i> recovery was restored, so it proposed a quantitative pattern between <i>TOC</i> evolution and the main controlling factors. Then through giving a certain value for each factor that calculated the <i>TOC</i> recovery coefficient, the <i>TOC</i> evolution charts for muddy source rocks and carbonate source rocks in the case of different kerogen types were made. The main characteristic of this method was able to avoid the deviation that subjective factors and physical simulation experiment conditions might lead to.The results were as follows:With the increasing of thermal evolution level,the residual <i>TOC</i> in source rocks reduced gradually in large hydrocarbon expulsion stages(<i>R</i>_O=0.5％～2.0%); the reduction amount was biggest for source rocks in high mature-over mature stage(<i>R</i>_O&gt;1.2%); the recovery coefficient gradually increased with the increasing of <i>R</i>_O. The <i>TOC</i> recovery coefficients can respectively reached to 3.0,2.0, and 1.4 for muddy source rocks in case of kerogen types Ⅰ, Ⅱ, and Ⅲ;for carbonate source rocks,the <i>TOC</i> recovery coefficients were respectively 3.2,2.2, and 1.5. The practical applications of <i>TOC</i> recovery were exemplified in field.