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1.
海拉尔盆地碎屑岩储层束缚水饱和度的确定   总被引：4，自引：0，他引：4  
核磁测井资料确定束缚水饱和度主要是采用T2固定截止值法.随着对复杂岩性储层的勘探,近年来,在固定T2截止值方法基础上又发展了锥形T2截止值法、薄膜模型以及频谱模型.对于岩性多变、孔隙结构复杂的碎屑岩储层,常规测井方法和以T2截止值为基础的核磁测井方法确定的束缚水饱和度都难以满足测井评价的精度要求,这时需要考虑薄膜模型和频谱模型方法.这两种模型认为各种尺寸的孔隙中均含有束缚水,只是不同尺寸孔隙束缚水含量不一样.在对海拉尔盆地岩性多变、孔隙结构复杂的碎屑岩储层的实践中,对回波串数据作多指数反演拟合时采用了2的幂次方方式布点,相应地得到了核磁测井T2谱,并从中选取了9个孔隙组分,将其与反映粘土含量的中子-密度孔隙度差值结合,采用回归的方法得到了束缚水饱和度的计算公式.回归公式在海拉尔盆地取得了较好的应用效果,尤其是贝尔凹陷,预测效果提高了将近1倍,计算的束缚水饱和度与岩心分析束缚水饱和度相比,平均相对误差从15.1%减小到8.7%.  相似文献   

2.
Microscopic pore structure and water distribution are important and fundamental parameters for coalbed methane reservoir characterisation. These are closely related to the calculation/interpretation of other critical parameters, such as permeability and flow capacity. In this study, scanning electron microscopy, low-pressure nitrogen gas adsorption, nuclear magnetic resonance spectroscopy, and theoretical calculations were used to study the pore structure characteristics and water distribution of Zhaozhuang coal mine in the southeastern Qinshui Basin, PR China. The results show that the pore radius ranges from 2.066 to 594.045?nm, mainly classified as micropores and transitional pores. The micropores significantly contribute to the total pore volume. The adsorption pores (micropores and transitional pores) contribute the most to the total specific surface area. The T2 spectrum distributions of saturated water samples show two peaks. The first T2 spectrum peak is related to adsorption pores, whereas the second T2 spectrum peak is related to seepage pores. The seepage pores were not well developed as the adsorption pores. Most adsorption pores are saturated with irreducible water that could not be discharged by centrifugation, whereas the seepage pores are saturated with movable water that could be completely discharged by centrifugation. The T2 cutoff method was used to calculate the irreducible water saturation, and the irreducible water saturation of the sample was ≥90%. The irreducible water was mainly distributed in the micropores, and some of the irreducible water was distributed in the transitional pores. The irreducible water that remains in the pores can cause reservoir damage.  相似文献   

3.
The methods of nuclear magnetic resonance(NMR)spectroscopy,mercury injection porosimetry(MIP),and gas-water relative permeability(GWRP)were used to reveal the pore structure and permeability characteristics of high-rank coal reservoirs in the Bide-Santang basin,western Guizhou,South China,to provide guidance for coalbed methane(CBM)exploration and exploitation and obtain direct insights for the development of CBM wells.The results indicate that the coal reservoirs in the study area are characterized by well-developed adsorption pores and poorly developed seepage pores.The bimodal NMR transverse relaxation time(T2)spectra and the mutation in the fractal characteristic of the MIP pore volume indicate poor connectivity between the adsorption pores and the seepage pores.As a result,the effective porosity is relatively low,with an average of 1.70%.The irreducible water saturation of the coal reservoir is relatively high,with an average of 66%,leading to a low gas relative permeability under irreducible water saturation.This is the main reason for the low recovery of high-rank CBM reservoirs,and effective enhanced CBM recovery technology urgently is needed.As a nondestructive and less time-consuming technique,the NMR is a promising method to quantitatively characterize the pores and fractures of coals.  相似文献   

4.
为分析准噶尔盆地南缘（简称准南）低煤阶煤储层可动流体、束缚流体以及孔径分布特征,对准南6个矿区6个煤样进行了高速离心和低场核磁共振实验。实验结果表明:准南低煤阶煤以吸附孔发育最优,其次为渗流孔和裂隙。建立束缚水状态的最佳离心力为1.380 MPa;结合饱和水状态和束缚水状态的核磁共振T2谱,得到可动流体孔隙度为0.45%~1.89%,平均1.29%;束缚流体孔隙度为1.03%~7.45%,平均4.18%,可动流体孔隙度与渗透率呈幂指数关系（R2=0.935 8）。根据"离心-T2C法"得到准南低阶煤孔隙半径主要分布在0.01~1 μm,平均孔隙半径为1.771 μm。   相似文献   

5.
致密砂岩储层是油气勘探的重点方向之一,由于致密砂岩储层具有低孔低渗、孔隙结构复杂、非均质性强和岩电参数变化等特点,在测井解释过程中不同于常规储层。Archie公式在致密砂岩地层中使用时,强非均质性导致岩电参数a、b、m和n会随着储层的变化而变化。针对苏里格西区盒8段致密砂岩储层提出利用变岩电参数建立饱和度模型。依据研究区盒8段储层25块岩心岩电实验分析发现胶结系数m与lgϕ呈二次函数关系、m与岩性系数a呈幂函数关系、束缚水饱和度Swb对饱和度指数n有较大的影响。因此,在对孔隙度、束缚水饱和度和孔隙结构指数等因素分析的基础上,综合各因素影响特征建立了变岩电参数的饱和度模型。结果表明,该方法相对传统Archie公式饱和度解释,模型精度更高,为解释复杂孔隙结构砂岩储层提供了一种有效预测方法。  相似文献   

6.
广安气田上三叠统须四段和须六段气藏发育了构造气藏、构造-岩性气藏和岩性气藏.储层具有低孔、低渗、低阻和高束缚水饱和度特征.空间上,储层孔渗相关关系变化大,气水分布复杂,气水层识别困难.根据岩心对测井的标定,研究了须四段和须六段四性关系,认识到储层为细砂岩、中砂岩和粗砂岩,具有低自然伽马、低补偿密度、低电阻率和高声波时差特征,而物性与含气性无明显相关性.采取了分层、分区块建立储层孔隙度、渗透率模型,提高了物性解释精度.不同气藏类型具有不同的气水分布,应用阵列感应、核磁共振和综合判识3种方法进行了气水层识别,提高了广安气田气水层识别精度.这些方法在广安气田的应用表明可以准确识别构造气藏和构造-岩性气藏的气、水层,但对构造幅度低的岩性气藏识别精度不高,因为在这些岩性气藏中气水分异不彻底,气层与气水同层、水层含水饱和度是渐变的.   相似文献   

7.
核磁共振测井在低孔低渗油气层识别中的应用   总被引：2，自引：1，他引：2  
张宇晓 《新疆地质》2004,22(3):315-318
核磁共振测井具有常规测井无法比拟的优势，它可直观准确地提供储集层的孔隙度、渗透率，区分可动流体和束缚流体．根据差谱分析可以定性的识别油水层．通过求解地层的束缚流体饱和度，结合电阻率测井，采用阿尔奇饱和度解释模型，进行了油(气)层的识别和含油(气)饱和度的计算，从而拓宽了核磁共振测井资料的应用范围，为低孔低渗油(气)层的评价提供了一种新的途径．  相似文献   

8.
The Eocene rock units of the Qadirpur field, Central Indus Basin (Pakistan), are investigated petrophysically for their detailed reservoir characterization. The different petrophysical parameters determined include the following: true resistivity, shale volume, total porosity, effective porosity, density and neutron porosity, water and hydrocarbon saturation, bulk volume of water, lithology, gas effect, P-wave velocity, movable hydrocarbon index and irreducible water saturation and integrated with different cross-plots. The Eocene reservoirs are excellent with high effective porosity (2–32 %) and hydrocarbon saturation (10–93 %). Among these, the Sui Upper Limestone is an overall a poor reservoir; however, it has some hydrocarbon-rich intervals with high effective porosity and better net pay. All the net pay zones identified show low and variable shale volume (5–30 %). The secondary porosity has added to the total and effective porosities in these reservoirs. The main contributors to the porosity are the chalky, intercrystalline and vuggy/fracture types. The thickness of the reservoirs zones ranges from 4.5 to 62 m. These reservoirs are gas-producing carbonates with almost irreducible water saturation (0.002–0.01) and are likely to produce water-free hydrocarbons. The lower values of moveable hydrocarbon index (0.07–0.9) show that the hydrocarbons are moveable spontaneously to the well bore. The proposed correlation model shows that the reservoirs have an inclined geometry and are a part of an anticlinal trap.  相似文献   

9.
To accurately measure and evaluate reserves is critical for ensuring successful production of unconventional oil and gas. This work proposes a volumetric model to evaluate the tight sandstone gas reserves of the Permian Sulige gas field in the Ordos Basin. The reserves can be determined by four major parameters of reservoir cutoffs, net pay, gas-bearing area and compression factor Z, which are controlled by reservoir characteristics and sedimentation. Well logging, seismic analysis, core analysis and gas testing, as well as thin section identification and SEM analysis were used to analyze the pore evolution and pore-throat structure. The porosity and permeability cutoffs are determined by distribution function curve,empirical statistics and intersection plot. Net pay and gas-bearing area are determined based on the cutoffs, gas testing and sand body distribution, and the compression factor Z is obtained by gas component. The results demonstrate that the reservoir in the Sulige gas field is characterized by ultralow porosity and permeability, and the cutoffs of porosity and permeability are 5% and 0.15×10~(–3) μm~2, respectively. The net pay and gas-bearing area are mainly affected by the sedimentary facies, sand body types and distribution. The gas component is dominated by methane which accounts for more than 90%, and the compression factor Z of H_8(P_2h_8) and S_1(P_1s_1) are 0.98 and 0.985, respectively. The distributary channels stacked and overlapped, forming a wide and thick sand body with good developed intergranular pores and intercrystalline pores. The upper part of channel sand with good porosity and permeability can be sweet spot for gas exploration. The complete set of calculation systems proposed for tight gas reserve calculation has proved to be effective based on application and feedback. This model provides a new concept and consideration for reserve prediction and calculation in other areas.  相似文献   

10.
《Chemical Geology》1999,153(1-4):53-79
Marine sediment sequences with CH4 hydrate are characterized by an atypical depth profile in dissolved Cl− squeezed from pore space: a shallow subsurface Cl− maximum overlies a lengthy and pronounced Cl− minimum. This pore water Cl− profile represents a combination of multiple processes including glacial–interglacial variations in ocean salinity, advection and diffusion of ions that are excluded during gas hydrate formation at depth, and release of fresh water from dissociation of hydrate during core recovery. In situ quantities of gas hydrate can be determined from a measured pore water Cl− profile provided the in situ pore water signature prior to core recovery can be separated. Ocean Drilling Program (ODP) Site 997 was drilled into a large CH4 hydrate reservoir on the Blake Ridge in the western Atlantic Ocean. Previously we have constructed a high-resolution pore water Cl− profile at this location; here we present a `coupled chloride-hydrate' numerical model to explain basic trends in the Cl− profile and to isolate in situ Cl− concentrations. The model is based on thermodynamic and ecological considerations, and uses established equations for describing chemical behavior in marine sediment–pore water systems. The model incorporates four key concepts: (1) most gas hydrate is formed immediately below the SO42− reduction zone; (2) fluid, dissolved ions and gas advect upward through the sediment column; (3) CH4 hydrate dissociates at the base of hydrate stability conditions; and (4) seawater salinity fluctuates during glacial–interglacial cycles of the late Pliocene and Quaternary. Rates of upward advection in the model are sufficient to account for measured Br− and I− concentrations as well as CH4 oxidation at the base of the SO42− reduction zone. In situ pore water Cl− inferred from the model is similar to that determined by limited direct sampling; in situ CH4 hydrate amounts inferred from the model (an average of about 4% of porosity) are broadly consistent with those determined by direct gas sampling and indirect geophysical techniques. The model also predicts production of substantial quantities of free CH4 gas bubbles (>2.5% of porosity) at a depth immediately below the lowest accumulation of CH4 hydrate in the sediment column. Our explanation for the pore water Cl− profile at Site 997 is important because it provides a theoretical mechanism for understanding the distribution of interstitial water Cl−, gas hydrate, and free gas in a marine sediment column.  相似文献   

11.
Very limited investigations have been done on the numerical simulation of carbon dioxide (CO2) migration in sandstone aquifers taking consideration of the interactions between fluid flow and rock stress. Based on the poroelasticity theory and multiphase flow theory, this study establishes a mathematical model to describe CO2 migration, coupling the flow and stress fields. Both finite difference method (FDM) and finite element method (FEM) were used to discretize the mathematical model and generate a numerical model. A case study was carried out using the numerical model on the Jiangling sandstone aquifer in the Jianghan basin, China. The rock mechanics parameters of reservoir and overlying strata of Jiangling depression were obtained by triaxial tests. A two-dimensional model was then built to simulate carbon dioxide migration in the sandstone aquifer. The numerical simulation analyzes the carbon dioxide migration distribution rule with and without considering capillary pressure. Time-dependent migration of CO2 in the sandstone aquifer was analyzed, and the result from the coupled model was compared with that from a traditional non-coupled model. The calculation result indicates a good consistency between the coupled model and the non-coupled model. At the injection point, the CO2 saturation given by the coupled model is 15.39 % higher than that given by the non-coupled model; while the pore pressure given by the coupled model is 4.8 % lower than that given by the non-coupled model. Therefore, it is necessary to consider the coupling of flow and stress fields while simulating CO2 migration for CO2 disposal in sandstone aquifers. The result from the coupled model was also sensitized to several parameters including reservoir permeability, porosity, and CO2 injection rate. Sensitivity analyses show that CO2 saturation is increased non-linearly with CO2 injection rate and decreased non-linearly with reservoir porosity. Pore pressure is decreased non-linearly with reservoir porosity and permeability, and increased non-linearly with CO2 injection rate. When the capillary pressure was considered, the computed gas saturation of carbon dioxide was increased by 10.75 % and the pore pressure was reduced by 0.615 %.  相似文献   

12.
舒萍 《世界地质》2010,29(1):83-89
通过徐深气田天然气气体状态方程( PVT) 性质、天然气饱和水汽量和地层水PVT性质测试及全直径岩芯分析的气藏启动压力、储层流速敏感性和应力敏感性评价, 探讨了火山岩储层渗流机理。结果表明: 徐深气田火山岩气藏中CO2含量差别较大(最高达86.88% ) , 天然气分子量与CO2含量呈正相关; 偏差系数、饱和水汽含量及地层水中天然气含量受地层温度、压力、天然气组成及地层水矿化度等影响; 火山岩气藏启动压力与束缚水饱和度和空气渗透率均呈幂指数关系; 储层呈气水两相流特征, 具有弱速敏性和较强的应力敏感性, 易造成储层渗透率伤害以及孔隙结构改变。  相似文献   

13.
为了研究高煤级煤储层含水性对吸附能力的影响,对阳泉-寿阳区块8件代表性煤样开展了镜质体反射率、显微组分、孔隙度、压汞、核磁共振和甲烷等温吸附等实验,分析了煤储层孔径分布、核磁共振T2谱响应特征、核磁孔隙度以及煤岩吸附能力,同时对煤储层含水性和煤储层吸附能力的相互关系进行了分析。研究结果表明：高煤级煤储层孔隙以微孔发育为主,孔隙含水性以微小孔中的束缚水赋存状态为主,且其含水量随最大镜质体反射率(Ro,m)的增大而增加。在影响高煤级煤储层吸附能力的多种因素中,煤储层含水性对煤岩吸附能力起着决定性的作用,尤其体现在微小孔中的束缚水对吸附能力的影响,束缚水含量越高,煤岩吸附能力越差。  相似文献   

14.
李忠  寿建峰  王生朗 《地质科学》2000,35(1):96-104
东濮凹陷低渗致密储层的沉积-成岩特征表现为砂层薄、粒度细、沉积非均质性显著;埋藏深度大于3700m,压实作用、晚期自生伊利石-绿泥石和二氧化硅胶结作用强。储层具有小孔极细喉孔隙结构,表面积大,渗透率对围压的敏感性强,地下真实孔隙度和渗透率分别介于10% -< 5% 、0.1×10-3-< 0.001×10-3μm 2.研究认为,东濮凹陷致密砂岩气藏大多产出于盆地次级深洼陷中,具有高压水溶气的成因机制,这是由储层的低渗性、较高的毛细管准数、高束缚水饱和度和高温-高压以及充足-近源的天然气供给等条件所决定的。  相似文献   

15.
鄂尔多斯盆地西缘麻黄山地区延8储层特征   总被引：2，自引：0，他引：2  
通过对延8储层铸体薄片、扫描电镜、孔渗测定、压汞资料等分析,延8储层具有以下特征：研究区北边富长石、南边富石英,具有不同的物源;砂岩粒度以中粒为主,细粒和粗粒次之;主要的储集空间为粒间孔和粒内溶孔;由于大量的长石、岩屑被溶,孔隙度、渗透率不呈正态分布,均偏大,溶蚀作用形成的大量微孔造成高束缚水饱和度,产纯油或含水率极低;砂体厚度、岩石相和成岩作用共同控制着储集层的物性。结果表明,位于河道中部弱胶结的中砂岩具有良好的储集性能。  相似文献   

16.
为了有效指导储层描述、评价及产能预测,为致密砂岩油气勘探和开发提供理论依据,以鄂尔多斯盆地临兴地区致密砂岩储层为例,利用铸体薄片、X射线衍射、核磁共振、高压压汞、气水相渗及扫描电镜等实验,分析了致密砂岩中束缚水饱和度的影响因素.结果表明:研究区致密砂岩束缚水饱和度为３４．７７％~８３．７８％,平均值为６３．８６％,T２谱截止值(T２cutoff)为３．８６~６５．６０ms,平均值为２０．９６ms;致密砂岩束缚水饱和度受储层物性、润湿性、敏感性、黏土矿物类型、质量分数和粒径共同作用;致密砂岩粒径越细,黏土矿物质量分数越高,岩石亲水性越强,岩石比表面积和水膜厚度越大,则毛细管束缚水和薄膜束缚水越高;水敏和盐敏是造成致密储层渗透率改变的主要因素;致密砂岩发育残余粒间孔、粒间溶蚀孔、粒内溶蚀孔、晶间孔和微裂缝;充填于孔隙中黏土矿物的类型、形态存在差异,致使致密砂岩储层的孔隙结构复杂,微观非均质性强,束缚水饱和度变化大.  相似文献   

17.
With the aim of better understanding the tight gas reservoirs in the Zizhou area of east Ordos Basin, a total of222 samples were collected from 50 wells for a series of experiments. In this study, three pore-throat combination types in sandstones were revealed and confirmed to play a controlling role in the distribution of throat size and the characteristics of gas-water relative permeability. The type-Ⅰ sandstones are dominated by intercrystalline micropores connected by cluster throats, of which the distribution curves of throat size are narrow and have a strong single peak(peak ratio 30%). The pores in the type-Ⅱ sandstones dominantly consist of secondary dissolution pores and intercrystalline micropores, and throats mainly occur as slice-shaped throats along cleavages between rigid grain margins and cluster throats in clay cement.The distribution curves of throat size for the type-Ⅱ sandstones show a bimodal distribution with a substantial low-value region between the peaks(peak ratio 15%). Primary intergranular pores and secondary intergranular pores are mainly found in type-Ⅲ samples, which are connected by various throats. The throat size distribution curves of type-Ⅲ sandstones show a nearly normal distribution with low kurtosis(peak ratio 10%), and the micro-scale throat radii(0.5 μm) constitute a large proportion. From type-Ⅰ to type-Ⅲ sandstones, the irreducible water saturation(Swo) decreased; furthermore, the slope of the curves of Krw/Krg in two-phase saturation zone decreased and the two-phase saturation zone increased,indicating that the gas relative flow ability increased. Variations of the permeability exist in sandstones with different porethroat combination types, which indicate the type-Ⅲ sandstones are better reservoirs, followed by type-Ⅱ sandstones and type-Ⅰ sandstones. As an important factor affecting the reservoir quality, the pore-throat combination type in sandstones is the cumulative expression of lithology and diagenetic modifications with strong heterogeneity.  相似文献   

18.
The Upper Paleozoic section contains a tight gas sandstone reservoir (of 2.75 × 1012 m3) in the Ordos Basin, central China. The measured porosities (< 10%) and permeabilities (generally < 1 mD) are the result of significant mechanical and chemical compaction and precipitation of carbonate, quartz and authigenic clay cements. Fluid inclusion geochemistry and kinetic modeling (generation of gaseous components and δ13C1) were integrated to constrain the timing of gas charge into the tight reservoir. The modeling results indicate that the natural gases in the present reservoir are similar to gases liberated from quartz inclusions in both composition and stable carbon isotope values and also similar to gas generated from Upper Paleozoic coal. The similar geochemistry suggests that an important phase of quartz cementation must have occurred after gas emplacement in the reservoirs during regional uplift at the end of the Cretaceous. The latest carbonate cement, postdating quartz cementation, consumed most of the late CO2 generated from coal at high maturity (RO > 1.7%) and reduced the reservoir quality dramatically. On the contrary, tight sandstones from non-producing areas have fluid inclusions that were trapped in quartz cements much earlier. These data indicate that natural gas migrated into the Upper Paleozoic reservoir when it still retained high porosity and permeability. The reservoir continued to experience porosity and permeability reduction from continued quartz and carbonate cementation after gas charging due to low gas saturation. Comparison of the relative timing of gas charging with that of sandstone cementation can help to predict areas of risk during tight gas exploration and development.  相似文献   

19.
《China Geology》2022,5(3):383-392
To obtain the characteristics of the gas hydrate reservoirs at GMGS3-W19, extensive geophysical logging data and cores were analyzed to assess the reservoir properties. Sediment porosities were estimated from density, neutron, and nuclear magnetic resonance (NMR) logs. Both the resistivity and NMR logs were used to calculate gas hydrate saturations, the Simandoux model was employed to eliminate the effects of high clay content determined based on the ECS and core data. The density porosity was closely in agreement with the core-derived porosity, and the neutron porosity was higher while the NMR porosity was lower than the density porosity of sediments without hydrates. The resistivity log has higher vertical resolution than the NMR log and thus is more favorable for assessing gas hydrate saturation with strong heterogeneity. For the gas hydrate reservoirs at GMGS3-W19, the porosity, gas hydrate saturation and free gas saturation was 52.7%, 42.7% and 10%, on average, respectively. The various logs provide different methods for the comprehensive evaluation of hydrate reservoir, which supports the selection of candidate site for gas hydrate production testing.©2022 China Geology Editorial Office.  相似文献   

20.
吐哈盆地巴喀气田八道湾组致密砂岩气藏气水分布特征   总被引：1，自引：1，他引：0  
基于核磁共振、压汞测试、物性分析、相渗曲线及生产动态等多种资料,对吐哈盆地巴喀气田八道湾组致密砂岩储层的物性特征、孔喉分布、束缚水含量、气柱高度、"甜点"发育的主控因素进行了分析,总结了研究区气水分布特征和气水分布模式。研究结果表明:八道湾组发育典型的致密砂岩储层,其孔隙度总体小于7%,渗透率小于0.2×10-3μm2;喉道半径较小,主喉道半径的分布范围为0.01～1μm;束缚水饱和度较高,且同孔隙度呈负相关关系。研究区气水过渡带的范围约为640 m,研究区储层总体处于气水过渡带之内;处于过渡带不同构造位置处不同物性的储层具有不同的含气特征和气水生产特征,位于气水过渡带较高部位的物性较好的区域和裂缝发育区是"甜点"的主要发育区。  相似文献   

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