Taking the low-permeability reservoir of complex sandy conglomerate reservoir of Kongdian Formation in Bozhong structure as the research goal, the comprehensive discrimination method of fluid phase state category of low-permeability reservoir is studied. This article analyzes the division method, genesis, and geological characteristics of low-permeability reservoirs and the distribution law of fluid phase. Based on the gas state equation and gas liquid phase equilibrium equation, combined with thermodynamic theory, hydrocarbon fluid phase simulation is carried out by calculating bubble point pressure, dew point pressure, and other parameters. Combining the analysis results of fluid composition of typical wells, the fluid types of low-permeability reservoirs in complex glutenite reservoirs of Kongdian Formation in Bozhong structure are comprehensively distinguished by using phase diagram discrimination method and empirical statistical method of hydrocarbon composition combination parameters. The results show that the phase diagram discrimination method is consistent with the empirical statistical method of hydrocarbon composition combination parameters, and the discrimination accuracy of phase state category is close to 100 %. It is concluded that the low-permeability reservoir of complex sandy conglomerate reservoir of Kongdian Formation in Bozhong structure is mainly oil-free condensate gas reservoir.

In order to enhance oil recovery, supercritical CO2 (scCO(2)) flooding has been applied in many oilfields to extract oil and gas post primary recovery. However, it causes serious scaling problems in the reservoir, oil well and production tubing. In this article, the produced water quality before and after scCO(2) flooding in carbonate reservoirs are analyzed. The scaling trend of produced water before and after scCO(2) flooding was calculated by using the Davis-stiff saturation index and Ryznar stability index methods. Static experiments and scanning electron microscope (SEM) are used to study the scale inhibition performance and mechanism of HEDP, ATMP, MA-AA, and PAA on CaCO3 in produced water before and after scCO(2) flooding. The results show that after scCO(2) flooding, the quality of produced water changes obviously, thus the scaling trend of produced water increases, the growth of CaCO3 crystal is affected and the scale inhibition efficiency of conventional scale inhibitors decreases.

Overemphasizing the value of reefs in oil and gas exploration, reef-oriented geologists explain all carbonate platform deposits using the Wilson model.In their eyes, rimmed shelves are more valuable than carbonate ramps.However, organic banks are excellent reservoirs generated by carbonate ramps in the study area, as verified beyond doubt through petroleum exploration, such as this thesis, which investigates the genesis, types, and distribution of carbonate deposition in the north zone of the Amu-Darya Basin.Monoclinal palaeogeomorphology and rudists suggest shallow environments.Given that oolite shoals and rudist patch reefs were observed in the study area, the depositional system is interpreted to be a carbonate ramp.The Callovian-Oxfordian stage consists of nine lithofacies: oolitic limestone, skeletal limestone, micritic limestone, bioturbated limestone, and crystalline limestone, which are grouped into three facies associations presenting outer ramp, mid-ramp, and inner ramp facies associations.Five depositional sequences can be distinguished in the Callovian-Oxfordian stage.Each third-order depositional sequence is composed of transgressive systems tracts (TST) and highstand systems tracts (HST).The TST consists of mudstones with a higher response to natural gamma rays, whereas the HST contains various types of grainstone, with subordinate dolostone.The vertical and lateral distributions of sedimentary facies, and their interpreted depositional environments, revealed a ramp exhibiting a gradual southeast-northwestward environmental change from outer ramp, mid ramp, and inner ramp carbonate facies.

开展西沙海域碳酸盐台地识别及模式总结,不仅具有油气勘探指导意义,而且能丰富碳酸盐岩沉积学理论.基于高分辨率三维、区域二维地震资料,利用古地貌分析,结合碳酸盐岩沉积学类比,确定了南海西北深水区碳酸盐台地类型及展布,分析了其演化过程.认为南海西北深水区中中新世开始发育碳酸盐台地,据构造背景(Ⅰ级)、地理位置(Ⅱ级)将其划分为离岸碳酸盐台地(中中新世)和孤立碳酸盐台地(晚中新世)两大类,据镶边性(Ⅲ级)和坡度(Ⅳ)进一步细分为:离岸台地镶边岛架、离岸台地缓坡、离岸台地陡坡,孤立台地镶边岛架、孤立台地缓坡、孤立台地陡坡等亚类.南海西北部台地经历了由西向东的迁移过程.古地貌和海平面变化是该地区碳酸盐台地生长、持续、消亡的两大主控因素,陆坡隆起控制碳酸盐台地发育范围、规模和迁移方向;凸起控制碳酸盐台地类型、相带和迁移速度;半地堑作为外源容纳空间和输出通道而保证了碳酸盐台地发育的“水清”环境;台地边缘形态决定碳酸盐台地高能相带的分布、类型和规模.海平面上升导致碳酸盐台地由西向东退积,台地面积减小,环礁发育程度趋向成熟.

近年来深水勘探已成为寻找油气的重要领域,白云凹陷在早中新世经历了复杂的构造沉积环境,解剖深水层序模式有利于揭示深水沉积演化规律.通过井震结合及属性分析对白云凹陷早中新世层序地层进行研究,识别出3个层序界面:ZJSB1(23.8 Ma),ZJSB2 (22 Ma),ZJSB3 (21 Ma).其中ZJSB1、ZJSB3为重大不整合面,ZJSB2为水道下切侵蚀面.与之对应的界面发育3套层序:ZJSQ1,ZJSQ2,ZJSQ3.由于白云凹陷构造运动及古地貌的差异性,总结了2套深水层序模式:水道-深海披覆泥层序模式与块状搬运复合体-砂质碎屑流深海扇-水道-深海泥层序模式,在不同的演化阶段,前者主要受海平面的变化控制,而后者是受构造和海平面双重影响的.而同一地质时期古地貌又控制了沉积发育,高地势区发育下切水道,而低洼区发育深海披覆泥岩.因此,深水层序模式下研究深海沉积单元,对指导深水沉积和油气勘探具有极其重要的意义.

The styles of salt structures developed on the west-Africa margin and their evolutionary mechanism and controlling factors are studied upon 3-D seismic data.The thin-skin structures were formed due to the gliding of the overlying strata,characterized by a compressional deformation zone in the frontier area and an extensional deformation zone on the backside,with a transitional zone in between.Salt rafts,pre-rafts and monocline structures develop in the extensional area,whereas the transitional deformation zone is characterized by various extensional diapirs.Squeezed diapir and allochthonous sheets are well developed in the compressional deformation zone.Gravity gliding is the driving force of the salt tectonics on the passive margin throughout the forming time.Gravity spreading derived from the differentiation of sediment load significantly controls the salt tectonics in the stage while the margin is mature,but weak in the early time.Tectonic activity at the continental margin is the main factor which triggers salt tectonics which starts after the cessation of tectonic activities.Differentiation of sediment load influences the decollement of strata overlying the salt,and the topography below the salt layer has significant impacts on the salt flowing,the slipping velocity of the strata,the generation of related faults and the responses of sedimentation.

Based on the reflection and architectural characteristics of the high resolution seismic data,and combined with the cyclic variations of seismic attribute,the Miocene sedimentary sequence can be divided into three sequence groups and six 3rd-order sequences in the deep-water region,Southern Qiongdongnan Basin.From bottom to top,three sequence groups correspond to Sanya,Meishan and Huangliu Formations respectively.In the sequence framework,six types of typical seismic facies are indentified,which include moundy seismic facies,progradational seismic facies,channel-filled seismic facies,chaotic seismic facies,wavy seismic facies as well as parallel and sub-parallel seismic facies.Wavy reflection and parallel and sub-parallel reflection mainly develop in Sanya Formation while the moundy and wavy reflections dominates in Meishan Formation.Reefs thrived rapidly during Meishan age.Moundy and wavy reflections remained dominant but the scale of the moundy reflection was obviously minishing in Huangliu Formation compared with that in Meishan Formation.The whole Miocene sequence displayed a transgression progress in which the sedimentary environments changed from littoral and neritic to shallow marine and then gradually transited to bathyal so that fan deltas,reef shoals and channel sedimentary systems developed.It is known that the distribution and evolution of seismic facies are obviously controlled by the evolution of the sedimentary systems.It is suggested that the reefs and channel sediments may be the favorable hydrocarbon reservoirs.

Based upon high resolvable 3D seismic data as well as seismic attributes,a great many gas chimneys are discovered in deepwater Baiyun Sag,the Pearl River Mouth Basin.A gas chimneys can be divided into three components: the root,the leakage zone and the top of the leakage zone.Every one may be of different seismic reflection anomaly including lateral changes of events,local amplitude,frequency and continuity.The roots of gas chimneys are the initial parts of releasing gas pressure and also the source of supplying gas.The leakage zones are the main parts of whole gas chimneys for fluid to pass through.Gas reservoirs are commonly present at the tops of the leakage zones.Two models related with gas accumulation are built.One is the model of gas accumulation at the flanks and the other is the one at the tops of gas chimneys.The hydrocarbon in those chimneys is all derived from Paleogecene to Neogene lacustrine sediments.

Amu-Darya Basin is one of the significant large potential petroliferous basins in Middle Asia. Both Chardzhou and Bukhara terraces,which are located in the northeastern of Amu-Darya Basin,provide more than a half of petroleum resources volume of the basin. Rich hydrocarbon is accumulated dominantly in local anticlines and reef traps,which are closely relative with structural formation and evolution in this basin. On the basis on available geological data,fine stratigraphic correlation and seismic data interpretation,two key geological interfaces,the faulting-depression transform interface at the end of Jurassic and the regional angular unconformity at the end of Paleogene,are recognized and the relative deformation phases are defined according to the theory of plate tectonics. It is suggested that the important stages of Jurassic-Cretaceous faulted depression and Paleogene compressed uplifting-reformation have undergone within these terraces,which results in forming the upper,the middle and the lower synthems. The sedimentation in the faulted depression stage controlled the tectonic framework of this region and the development of the salt layers in the middle synthem advanced the succeeding tectonic patterns. Tectonic movements during Paleogene-Neogene time brought on extensive structure deformation in this region,which con-structs a series of typical structural belts such as thrust belts,strike-slip fault belts and asymmetrical composite anticline belts.