Conglomerate reservoir developed in fan-delta environment is characterized by the diverse lithofacies types and strong heterogeneity. Lithofacies type is the main primary factor that controls the reservoir physical properties. However, quantitative sedimentary texture parameters of lithofacies types are scarcely studied, and their influence on the reservoir physical properties are still poorly understood. In this paper, lithofacies type, sedimentary texture and pore type, porosity and permeability of the Baikouquan Formation in Mahu Sag were studied to reveal the control of sedimentary texture parameters on the reservoir physical properties. The results showed that (1) lithofacies types in Baikouquan Formation can be classified into Gcm1, Gcm2, Gcm3, Gcm4, Gc, Sm1, Sm2, MSm, SSr, SSp and Mh; (2) different sorting coefficient and matrix content are present in Gcm, Gc, Sm1, Sm2 and MSm. These two texture parameters are highest in Sm2 and MSm, below Gcm and Gc, and the lowest in Sm1; (3) intra-gravel microfracture, gravel-edge microfracture and intra-matrix microfracture develop in conglomerates, which can improve their permeability; (4) porosity in Gcm, Gc, Sm1, Sm2 and MSm and permeability in Sm1, Sm2 and MSm have negative correlations with their sorting coefficient and matrix content. However, permeability in Gcm and Gc have poor correlations with these two texture parameters due to microfractures; (5) Gc and Sm1 have relatively high porosity and permeability due to their good sorting, low matrix content and consequently strong dissolution. By contrast, Gcm, Sm2 and MSm have relatively low porosity and permeability due to their bad sorting, high matrix content and consequently weak dissolution. These results indicate that Gc and Sm1 deposited in subaqueous distributary channels and lobes should be the first target in hydrocarbon exploration of fan-delta conglomerate reservoir.

MH1 井区主体位于玛湖凹陷南斜坡区,作为南斜坡区重点开发区域,MH1 井区目前仍存在沉积相认识不精确、储层分类不明确等问题.通过岩心观察、结合测录井资料,进行沉积微相精细描述及有利储层分布预测研究.结果表明:MH1 井区二叠系下乌尔禾组为一套由西北向东南发育的扇三角洲相,可识别出 9 个沉积微相类型,根据扇三角洲前缘的岩性分布,将前缘划分为内外前缘.根据试油资料,发现主要有利储层集中在内前缘部分.根据孔隙度、渗透率,将MH1 井区下乌尔禾组储层分为3 类.其中Ⅰ类储层孔隙度渗透率均为最好,为有利储层,Ⅱ类储层次之,Ⅲ类储层孔隙度、渗透率均为最差,作为非储层类型.研究结果为MH1 井区下乌尔禾组后续的评价、开发提供新的地质依据,为其他扇三角洲发育区的油气勘探评价提供借鉴.

The Lower Wuerhe Formation in Mahu 1 well area of Junggar Basin is rich in oil and gas resources, which are rich in zeolite cements. In this paper, based on core observation and scanning electron microscope data, we clarified that there are four types of zeolite minerals, mainly turbidite, followed by zeolite, and occasionally zeolite and clinoptilolite. Based on the data of X-ray diffraction, physical properties and thin sections, there are two genetic modes of zeolite minerals in this area: cementation and volcanic erosion. For the first time, the prediction model of zeolite content was established by the method of multiple regression, and the plane distribution map of the content of turbidized zeolite in the target strata in the study area was established. The study found that zeolite mainly distributed in the conglomerate size in fine conglomerate and small conglomerate, and the microfacies mainly distributed in the front zone of fan delta.

Marine organic-rich shale is widely distributed in the Upper Ordovician Wufeng Formation (WF-F) and Silurian Longmaxi Formation (LMX-F), making it an important target for shale gas exploration and development. In order to clarify the paleoenvironment evolution characteristics and the effect of depositional environment on organic matter (OM) accumulation of the marine shale in the Wufeng and Longmaxi Formations, a series of geochemical and petrological experiments were carried out, including TOC, Rock-Eval pyrolysis, XRD, and major and trace element analyses. Research results show that based on the variation characteristics of TOC, mineral composition, and paleoenvironment evolution characteristics, four units can be identified from bottom to top: Wufeng Formation (WF-F), Lower Longmaxi Formation (L-LMX-F), Middle Longmaxi Formation (M-LMX-F) and Upper Longmaxi Formation (U-LMX-F). The high-quality marine shale developed in WF-F and LMX-F in the Zigong area (TOC: 0.65–4.56%, avg. 2.15%) contains type I kerogen (kerogen type index: 86.0–98.3, avg. 92.7) and OM in mature stage (average of Rb and Tmax are 2.94%, 646 °C, respectively). Clay minerals (avg. 42.5%) and quartz (avg. 37.7%) dominate the mineral compositions, with subordinated dolomite (avg. 6.3%), feldspar (avg. 6.0%), calcite (avg. 4.0%), and pyrite (avg. 3.5%). Paleoenvironment indicators suggest that during the sedimentary period of WF-F and L-LMX-F, the paleoclimate condition was humid; the weathering condition, paleosalinity, and redox conditions were the strongest; and there was a relatively high level of paleoproductivity and a relatively low level of terrigenous detritus influx. However, during the period of M-LMX-F and U-LMX-F, the climate gradually changed from warm and humid to hot and dry; the intensity of weathering conditions, paleosalinity, and redox conditions was relatively reduced; terrigenous detritus influx increased; and the paleoproductivity decreased. Relationships between TOC and paleoclimate condition, paleosalinity, redox condition, paleoproductivity, and terrigenous detritus influx suggest that redox condition is most important controlling factor for OM enrichment. A combination of anoxic bottom water conditions and high primary productivity and a relatively low terrigenous input resulted in the enrichment of OM in the WF-F and L-LMX-F, making it a potential exploration and development target. The research can provide scientific guidance for the selection of potential shale gas development targets in the Zigong area.

In order to clarify the diagenesis of the conglomerate reservoir in the Lower Wuerhe Formation in Mahu 1 well area, Junggar Basin, the reservoir in the study area was studied in detail on the basis of core observation, thin section identification and analysis data. The results show that the Lower Wuerhe Formation is a reservoir with low porosity and low permeability. The pore types are mainly residual intergranular pores, followed by dissolution pores, and occasionally structural fractures and microfractures. The reservoir physical property is closely related to the rock facies type, among which the fine conglomerate is the best, the small conglomerate is the second, and the middle conglomerate is the worst. The Lower Wuerhe Formation in the study area mainly experienced diagenesis such as compaction, cementation and dissolution. In the later stage of diagenesis, zeolite minerals were transformed and dissolved, and a large number of dissolution pores were formed, which had a positive effect on reservoir physical property and oil content. Through three solution pore porosity intersection method to establish evaluation model, and solution pore zeolites in the studied area development situation to carry on the quantitative evaluation, fine recognition, effectively guide the advantage dessert for reservoir evaluation and subsequent development provides new ideas and methods, as well as neighbors area and the development of other clastic rock area reservoir development for reference.

Abundant hydrocarbon resources were discovered in the Xiazijie fan-delta in the Triassic Baikouquan Formation in Mahu sag, Junggar Basin. However, the maximum depositional age of Baikouquan Formation and provenance of this fan-delta are still unclear, which would be unfavourable for further hydrocarbon exploration. In this study, we used detrital zircon U-Pb dating and composition statistics of conglomerate clast and sandstone grain from Baikouquan Formation to constrain the maximum depositional age and provenance of the Xiazijie fan-delta. The results showed that (1) the conglomerate clast compositions of Xiazijie fan-delta mainly consisted of tuff and intermediate-felsic magmatic rocks, and sandstone samples could be classified as litharenite type with the lithic fragments were almost entirely volcanic lithic fragments; (2) the average Qt:F:L values of sandstone samples (M152-S1 and M152-S2) were 26:7:67 and 21:8:71, respectively, and they plotted in the magmatic arc domain in the Qt-F-L ternary diagram, indicating the tectonic setting of source area of Xiazijie fan-delta was magmatic arc; (3) M152-S1 yielded U-Pb ages ranging from 417 Ma to 253 Ma, with a dominant age peak at 313 Ma and two secondary age peaks at 411 Ma and 268 Ma, respectively, while M152-S2 yielded U-Pb ages ranging from 467 Ma to 256 Ma, with a dominant age peak at 307 Ma and two secondary date peaks at 405 Ma and 262 Ma; (4) the mean age of youngest two zircon grains of M152-S1 was 254.8 ± 4.7 Ma, while that of M152-S2 was 257.6 ± 3.8 Ma, suggesting the Baikouquan Formation might be deposited after the Changhsingian to Olenekian; (5) the magmatic rock ages of central West Junggar were distributed mostly between 450–260 Ma, with a dominant age peak at 307 Ma. The ages distribution between magmatic rock of central WJ and detrital zircons of M152-S1 and M152-S2 were similar, indicating the central WJ domain should be the major source area of the Xiazijie fan-delta; (6) the magmatic rock of Hakedun–Hongguleleng area in the Central WJ was characterized by a peak age at 305 Ma, which was consistent with the peak ages of M152-S1 and M152-S2, indicating the Hakedun-Hongguleleng area was likely to be their major source area; and (7) one minor peak age at 411 Ma and another at 405 Ma were obtained from M152-S1 and M152-S2, respectively, and a zircon grain with Middle Ordovician age at 467 Ma was obtained from M152-S2, indicating Late Silurian–Early Devonian Chagankule pluton in the Saier Mountain and Ordovician Honggleleng ophiolite mélange in the Sharburt mountain were the minor source areas. This research has significant implications for stratigraphic correlation in Junggar Basin and hydrocarbon exploration in the Xiazijie fan-delta conglomerate reservoir.

The identification of underground formation lithology is fundamental in reservoir characterization during petroleum exploration. With the increasing availability and diversity of well-logging data, automated interpretation of well-logging data is in great demand for more efficient and reliable decision making for geologists and geophysicists. This study benchmarked the performances of an array of machine learning models, from linear and nonlinear individual classifiers to ensemble methods, on the task of lithology identification. Cross-validation and Bayesian optimization were utilized to optimize the hyperparameters of different models and performances were evaluated based on the metrics of accuracy—the area under the receiver operating characteristic curve (AUC), precision, recall, and F1-score. The dataset of the study consists of well-logging data acquired from the Baikouquan formation in the Mahu Sag of the Junggar Basin, China, including 4156 labeled data points with 9 well-logging variables. Results exhibit that ensemble methods (XGBoost and RF) outperform the other two categories of machine learning methods by a material margin. Within the ensemble methods, XGBoost has the best performance, achieving an overall accuracy of 0.882 and AUC of 0.947 in classifying mudstone, sandstone, and sandy conglomerate. Among the three lithology classes, sandy conglomerate, as in the potential reservoirs in the study area, can be best distinguished with accuracy of 97%, precision of 0.888, and recall of 0.969, suggesting the XGBoost model as a strong candidate machine learning model for more efficient and accurate lithology identification and reservoir quantification for geologists.

为填补玛西斜坡白碱滩组在沉积学方面的空白,综合运用岩心、测井及分析化验等资料,对白碱滩组三段的沉积相进行了研究.结果表明:目的层属于辫状河三角洲相,共识别出辫状河三角洲前缘和前三角洲2个亚相,以及水下分流河道、支流间湾、河口砂坝、远砂坝及前三角洲泥等5个微相;在浅水沉积背景下,研究区内发育了来自西北和东北2个物源方向的辫状河三角洲前缘朵体,该前缘朵体自底部T3 b34小层到顶部T3 b31小层沉积时期,持续向湖盆中心方向不断进积;在T3 b32和T3 b31小层沉积时期,水下分流河道和河口砂坝砂体在研究区内大面积分布,由于其具有良好的内在储集物性条件和外在的构造圈闭与油气充注条件,可作为研究区后续油气勘探的首要目标.研究成果可为研究区白碱滩组未来的油气勘探提供有力的理论支撑.

玛湖凹陷M1井区上乌尔禾组砂砾岩储层非均质性强,孔隙结构和试油产能差异大,主控因素不明.利用岩心、薄片、测录井及试油等资料,对M1井区上乌尔禾组的沉积相、成岩相、裂缝相以及储层综合分类展开研究.结果表明,扇三角洲砂砾岩储层主要为重力流及牵引流2种成因类型,对应扇面河道、水下分支河道、泥石流3种沉积微相.可识别出弱成岩作用相、溶蚀相、压实致密相、方解石胶结相4种成岩相.沉积相与成岩相是影响该区储层的主控因素,依此将储层分为水下分流河道-弱成岩作用相、水下分流河道-溶蚀相、扇面河道-弱成岩作用相、扇面河道-溶蚀相、泥石流-压实致密相、砂砾岩方解石胶结成岩相6种岩石物理相.依据沉积相和成岩相对于储层的影响,将6种岩石物理相归纳为3种类型储层,其中Ⅰ类和Ⅱ类储层最好,Ⅲ类储层最差,胶结致密.该区岩石物理相与试油结果匹配好,可有效预测有利储层分布区.

准噶尔盆地玛湖凹陷西斜坡下三叠统百口泉组内,发育了世界上罕见的、最典型的大型扇三角洲.在岩芯沉积特征观察、岩石粒度与成分分析等基础上,结合测、钻井资料等,对该大型湖相扇三角洲的沉积特征与演化规律开展系统的研究,并建立了沉积与演化模式.结果表明:百口泉组沉积时期,玛西斜坡区发育了两个大型扇三角洲,其延伸距离可大于40 km;该扇三角洲相包含扇三角洲平原、扇三角洲前缘及前扇三角洲3个亚相,以及泥石流、扇面河道、碎屑流、水下分流河道、河口砂坝及前扇三角洲泥等9个微相;该扇三角洲富含砾质,总体上以重力流沉积(泥石流和碎屑流微相)的砾岩与牵引流沉积(扇面河道和水下分流河道微相)的砾岩、含砾砂岩交替叠置为特点;前缘环境的水下分流河道延伸近二十千米,且一直保持以砾质为主;纵向上,自百一段到百三段,该扇三角洲表现为典型的连续退积式,沉积演化规律十分清楚,其中,百一段沉积时期,该扇三角洲以扇三角洲平原占据主导地位,至百三段沉积时期,该扇三角洲则演化为以扇三角洲前缘为主,得益于水下分流河道的长距离延伸,使其依然保持为大型的扇三角洲.

The lower Wuerhe Formation reservoir in the eighth area of Karamay Oilfield is a fractured thick conglomerate reservoir with low-porosity and ultralow permeability. The development of this reservoir has always encountered problems such as inconsistency of injection and production, and ineffectiveness of water in oil wells. Fractures have a great impact on oil well development. Based on geological research, by starting from the fracture development degree of a single well and its corresponding water seeing with the combination of the corresponding relationship between injection and production of typical well patterns in fractured and non-fractured areas, the author established three water flooding modes: longitudinal water flooding, mixed water flooding and flat-water flooding. The research shows that the fracture development area is dominated by longitudinal water flooding and oil wells are liable to form fracture water channeling. The medium fracture development zone is dominated by plane water flooding, supplemented by vertical water flooding, that is, mixed water flooding, and oil wells have obvious results. The areas with no fractures developed shows the a planar water-flood, but the oil wells are relatively slow to take effect. The research results can provide a basis for the improvement of subsequent injection-production correspondence.

玛湖凹陷玛18井区多口井在百口泉组富泥储集层中试油获得高产,这与富泥段含油性差的传统认识相矛盾.为了探究富泥储集层收缩孔形成机理及其对储集层的影响,采用微米CT扫描实验技术和数字岩心计算方法对富泥储集层的三维孔隙结构开展研究,结果表明发育收缩孔的样品渗透率远高于不发育收缩孔的样品渗透率;采用原位电子探针技术对百口泉组泥质杂基的成分进行分析,结果表明高钾硅贫铁镁的泥质杂基在向云母类矿物转化过程中形成收缩孔;结合孔隙含量、孔隙度、渗透率和试油产量的多参数分析表明,收缩孔发育的富泥储集层段的孔隙度和渗透率并未因泥质含量增加而减小,反而呈现出增加的趋势;综合沉积相分析,玛18井区富泥储集层沉积环境为水下分流河道,广泛发育的收缩孔降低了泥质堵塞溶孔进而破坏储集层物性的程度.综合分析认为,高钾硅贫铁镁的泥质杂基在向云母类矿物转化时形成了收缩孔,收缩孔既扩充了岩石储集空间又沟通了其他类型的孔隙,进而改善富泥储集层的储渗能力,有利的沉积环境、优质的岩性和储集空间独特配置是富泥储集层成为优质储集层乃至获得高产的原因,其中,收缩孔的改造作用是关键因素.基于以上认识,利用测井图版识别出经过收缩孔改造的富泥储集层,试油效果良好,为玛湖地区挖潜增效提供了新的思路和方向.

哈萨克斯坦库姆萨伊盐上油田侏罗系发育一套曲流河三角洲沉积,为典型的高孔高渗储层.通过岩心观察、粒度分析、扫描电镜、岩石薄片等资料,首次对研究区储层的岩矿特征、物性以及孔隙结构进行了详细研究.研究表明:该区主要储集层岩性的为细砂岩、粉细砂岩,成分成熟度和结构成熟度均较高,呈现出远物源的沉积特征.黏土矿物以伊利石为主,其次为绿泥石和伊/蒙混层.砂岩储层孔隙类型以原生粒间孔为主,其次为次生的溶蚀孔隙,微裂缝少见.喉道类型以粗中孔粗中喉道为主,物性好,孔隙发育.在此基础上,进一步研究饱和度中值压力等影响因素,结合沉积微相、成岩作用等储层成因的主要控制因素,将侏罗系阿阿林阶组(Ю-I)分为Ⅰ、Ⅱ、Ⅲ类储层,巴柔阶组(Ю-Ⅱ)可划分为Ⅱ、Ⅲ类储层,同时通过最新的试油效果,验证了该区有利储层预测的可靠性和可行性,为该地区高孔高渗储层勘探开发提供了扎实的地质理论基础.

沉积相研究对控制储集砂体的空间展布有重要意义.为了对白25井区的沉积相类型进行有效的研究,在前人关于白25井区沉积相研究的基础上,结合白25井区的岩心资料、测录井资料,分析化验数据等相关资料后,认为白25井区上乌尔禾组发育的主要岩石相类型有:下部主要是红褐色、红色砂砾岩,发育块状构造;中部发育灰色、灰绿色砂砾岩,可见一定的粒序性,发育平行层理或交错层理.上部发育灰色、灰绿色砂岩以及泥岩,泥岩中可见水平层理.自下而上沉积物粒度逐渐变细,在垂向上反映了一个砂体不断向岸退积的沉积序列.白25井区上乌尔禾组发育的沉积相类型为扇三角洲,而不是冲积扇,可以识别出扇三角洲平原,扇三角洲前缘,前扇三角洲三个亚相以及扇面河道,水下分流河道等9个微相.

Permian Fengcheng Formation in well block 81 of Karamay Oilfield is developing the depositional system of braided river delta that is of braided rive to enter the lake.It gets the features of low porosity,extra-low permeability and intense heterogeneity.Through core analysis and logging data,there exist three sedimentary subfacies of braided river delta plain,including braided river delta font,braided river prodelta and sedimentary microfacies of channel lag.We have learnt of channel bar,overbank deposit,underwater distributary channel,bay,distributary mouth bar,distal bar,frontal delta mud etc.All are recognized.Distribution characteristics of each subfacies are analyzed,which provides the geological basis for favorable reservoir prediction in study area.

Permian Xiawuerhe Formation of Baikouquan block once developed a set of near - source coarse -grained clastic sediment. At present,a previous study of the data is less. Therefore,the oil field is facing an increasing contradiction in production. It had great difficulty in exploration and development of research work. Based on the observation of cores,including well logging,mud logging,we have made an analytical experiment data in sedimentary facies of Permian Xiawuerhe Formation. The results show that sedimentary facies in Xiawuerhe Formation is fan delta. The braided river delta and the main position is not in fan-delta front. The sedimentary facies can be divided into 2 subfacies of fan - delta front and frontal delta. We have discussed about 6 corresponding microfacies,such as debris flow and underwater branch river. Preliminary analysis of physical property data,underwater distributary channels to traction current genesis,will have better oil-bering properties than debris flow to generate to gravity flow. The study will provide new ideas and methods for the evaluation and follow-up development of this area,as is a reference for oil exploration and development to other near-area fan deltas in Karamay Oil Field.

The triassic Baikouquan formation of Ma 18 well block developed a set of near-source coarse-grained clastic sediment.At present,the type of sedimentary facies is still controversial in this region,and the contradiction of production is project.Based on the observation of cores,and combining scanning electron microscope,thin slices,well logging,mud logging and west testing data,sedimentary facies of triassic Baikouquan formation were studied.The results show that sedimentary facies in Baikouquan formation is fan delta,not alluvial fan or just only underwater deposition section of fan delta.The sedimentary facies can be divided into 3 subfacies of fan-delta plain,fan-delta front and frontal delta,and 9 corresponding microfacies,such as mud-rock flow and fan channel.Specifically,fan channel and underwater distributary channels belongs to traction current genesis,having better oil-bering properties than mud-rock flow and debris flow,generated to gravity flow.The study will provide new ideas and methods for the evaluation and follow-up development of this area,and provide references for oil exploration and development to near-area and oter fan deltas in China.

The Triassic Baikouquan Formation in Mahu slope area,Junggar Basin,attracted much attention of the reservoir sedimentologist.The difference of physical property in the sandy conglomerate reservoir is obvious,but its control mechanism has not been clear.According to the difference of fluid property,the rock facies are divided into four types:Traction current sandy conglomerate facies (TCSCF),pebbly sandstone facies,sandstone facies and gravity flow sandy conglomerate facies (GFSCF).During burial,compaction effect in the GFSCF is sooner and stronger than that in the TCSCF.And in the process of continuous deep burial,porosity in the GFSCF is not decreasing significantly,but the permeability begins increasing.These show there are micro-cracks beginning to produce in GFSCF.The difference of the compaction effect cause that type of reservoir space in the TCSCF is mainly dominated by primary intergranular pores,and secondary pores and micro-cracks is the main reservoir space in the GFSCF.Finally,the physical property of the TCSCF is obviously better than that of the GFSCF,the former is the effective reservoir in the formation.

为了解克拉玛依油田八区下乌尔禾组油藏注采对应关系的控制因素,提高油藏开发进程,在岩心观察的基础之上,结合录井、测井等资料的综合分析,首次将该研究区的砂砾岩按照成因机理,划分为牵引流砂砾岩、过渡类型砂砾岩及重力流砂砾岩,且牵引流砂砾岩的储层物性明显优于重力流砂砾岩.研究表明,若注入及采出井段岩性为牵引流砂砾岩,则可以有效的提高注采对应的有效性,过渡类型次之,重力流最差,进一步验证了该区牵引流砂砾岩和重力流砂砾岩的注采优劣关系.该成果将为该区下一步的开发提供坚实的地质理论及开发指导依据.

The upper Wuerhe formation of Upper Permian in District Wuba of Karamay oilfield in the northwestern margin of Junggar basin is a set of terrigenous coarse-grained clastic rocks.The main reservoir of the formation is sandy conglomerate and there are always some disputes on its sedimentary facies:alluvial fan,alluvial fan-fan delta or alluvial fan-nearshore subsea fan-fan delta.Further study on lithofacies will be benefit for accelerating the hydrocarbon exploration and development in the study area.By integrating data of core,rock thin section,lab analysis,mud log and well logging,the paper performs in-depth study on sedimentary characteristics of the formation.The study results show that the sedimentary facies of the upper Wuerhe formation in the study area is not an alluvial fan with its composite deposition system,but a set of typical fan delta depositions including 9 microfacies,i.e.,fan channel,debris flow and underwater distributary channel and so on.The paper also defines relationships between lithofacies and sedimentary microfacies.It is considered that the the physical property,oil-bearing property and formation test productivity of tractive-current sandy conglomerate are better than those of gravity-current sandy conglomerate,which could provide geological theory basis for future oil and gas exploration and development in the area.