玛湖凹陷百口泉组低渗砂砾岩油气藏成藏条件及富集规律

低渗砂砾岩油气藏是准噶尔盆地油气勘探的主要领域,目前玛湖凹陷西斜坡已发现并落实5个下三叠统百口泉组油藏。综合分析认为,玛湖凹陷西斜坡具备油气成藏的4大有利条件:二叠系多套高质量烃源岩持续供烃;低渗背景下发育储集层"甜点区";深大断裂与不整合面构成高效输导体系;区域性盖层发育。玛湖凹陷西斜坡百口泉组发育扇三角洲前缘有利相带,储集层物性较好,存在多期烃类充注,晚期高成熟油气保存条件较好,油质较轻并含气是油气富集的主要原因。

低孔低渗砂泥岩储层裂缝发育程度与产能关系

对于低孔低渗砂泥岩储层 ,孔隙度的大小与储层产能并没有很好的相关关系 ,因而 ,在过去的常规储层分析中 ,通常过多地考虑储层孔隙的发育程度而忽略了裂缝对其产能的影响。但是 ,随着测井技术的发展 ,特别是成像测井资料的应用 ,发现有些裂缝发育的低孔砂泥岩储层产能很高 ,裂缝起着储集和沟通流体的作用 ,从而提高和深化了对砂泥岩储层的认识。在低孔低渗砂泥岩储层中 ,由于孔隙度低 ,作为储层中流体的储集空间和孔隙之间连通性 (渗滤通道 )都较差。而裂缝在该类储层中有着储集空间和流体渗滤通道的双重作用 ,它既在储层中起沟通孔隙的作用 ,同时还起着储集流体的作用。因而 ,该参数在低孔低渗的砂泥岩储层中有着非常重要的作用。裂缝在砂泥岩储层综合评价和可改造性评价中越来越引起重视 ,特别是对于孔隙度较低的砂泥岩储层来说 ,裂缝对储层产能的影响相当大。

WS17-2低渗砂砾岩油藏注水/注气长岩心驱替效果评价及方案优选

岩心实验分析证实WS17-2低渗砂砾岩油藏储层具有微观非均质性强和水敏性强等特点,实施注水开发能否取得预期效果是开发方式选择的重要问题。分别采用短岩心拼接组合而成的组合长岩心、岩屑充填压实填砂管长岩心、组合全直径长岩心三种形式长岩心模型,开展了WS17-2油田流三段低渗砂砾岩油藏地层高温高压条件下注海水、注伴生气开发效果物理模拟及评价。结果表明,三种长岩心模型在水驱时均表现出较强的水敏伤害,导致注水压力过大;短岩心拼接模型和组合全直径模型注海水时均表现出突破较快,突破后驱油能力弱,提压效果差,最终采出程度低等特征,且驱油效果低于填砂管长岩心模型;相同长岩心模型下,注海水与注伴生气最终采出程度接近,但相同的注入量下注海水效果更好;海水驱后转注气驱可有效利用注入气的增溶膨胀、抽提、降黏、低张力作用,使原油采出程度在水驱基础上增加8~16个百分点;转注伴生气效果好于干气。实验结果可为此类海上低渗砂砾岩油藏的开发提供技术参考。

塔河油田石炭系低孔低渗砂砾岩储层水力加砂压裂技术探讨

针对塔河油田石炭系巴楚组砂砾岩储层埋藏深、地层温度高、岩性复杂、微裂缝发育等特点 ,在分析水力加砂压裂改造存在问题的基础上 ,对水力加砂压裂须做的前期研究工作和工艺技术的实施方案进行了探讨 。

承台基坑遇渗砂的施工处理方法

结合具体工程,通过对基坑施工时遇渗水、渗砂等现象的分析,提出了采用水下混凝土封底进行处理的方法,解决了承台基坑渗水、渗砂现象,从而达到了施工承台的条件,确保后续工序的施工。

基于海上砂砾岩低渗透率成因分析及测井评价

南海北部湾盆地乌石凹陷东区流沙港组三段以砂砾岩为主,岩石矿物类型多变、孔隙结构复杂、测井响应差异大,采用传统的地质统计回归方法很难准确求取储层渗透率。对流沙港组三段砂砾岩储层低渗透率成因分析的基础上,利用Bayes岩性判别原理建立岩相判别方程,对单井岩相进行数字划分,确定单井纵向上岩相类型,从而为储层渗透率的精细解释奠定基础。建立储层品质指数分级下的储层孔渗关系,认为储层品质指数可以作为储层孔隙度、渗透率与孔隙结构特征参数相互转换验证求取的中间桥梁。应用多矿物模型精确确定储层孔隙度,引入和建立储层孔隙结构参数与常规测井之间的定量关系,在岩相划分、孔隙结构特征分析和储层品质指数引入等地质研究基础上,采用非线性BP神经网络求取储层品质指数,进而反算砂砾岩储层渗透率。该方法提高了现有测井信息的利用率,解释结果与岩心和生产情况吻合度高,能够满足油藏描述和储量计算对参数精度的要求,可为南海西部相似低渗砂砾岩体的储层渗透率预测提供技术支撑。

“引渗管井与砂井”在基坑降水工程中的应用

阐述利用“引渗管井与砂井降水” ,成功的将浅层地下水引渗进入场区下部砂砾卵石层消纳 ,达到基坑干槽安全作业的实例 。

深层低孔低渗复杂砂砾岩储层岩性及渗透性表征规律研究——以J油田为例

J油田深层低孔低渗复杂砂砾岩储层岩性变化大、孔隙结构复杂、储层非均质性强,传统的孔隙度渗透率模型无法准确计算渗透率。利用物性分析试验数据和测井资料,对J油田深层低孔低渗复杂砂砾岩储层岩性及渗透性表征规律进行了研究,主要开展了岩性识别、孔隙结构评价和储层分类等工作,并在此基础上,建立了不同岩性的渗透率计算模型。计算结果与钻井取心资料符合度较高,有效提高了研究区深层低孔低渗复杂砂砾岩储层的测井解释精度。

深盆气高孔渗富气区块成因机理物理模拟实验与解析

实验表明,深盆气及其富气区块的压力并非一成不变,而是随着地质条件(供气强度和供气量)的变化呈周期性变化。深盆气富气区块与周边的致密砂体在深盆气的建设阶段各形成两套独立的正压(高于静水压力)压力系统,这是由于两者之间存在孔渗性差异。在深盆气的消亡阶段,两者压力均降低,直到负压(低于静水压力)并逐渐归一,其演变特征类似于正弦曲线。负压不是深盆气的基本特征,而只是深盆气形成演化过程中消亡阶段的一个特点。深盆气富气区块形成演化要经历深盆气初期充注阶段、临界接触时刻、"甜点"充气阶段、两气相连时刻、气藏扩展阶段和调整共溶阶段共6个阶段。控制深盆气富气区块成藏机理的动力是气体膨胀力、毛细管力和浮力,它们在深盆气富气区块成藏过程的不同阶段具有不同的表现和控制作用。从而建立了实验条件下较完整的深盆气富气区块成藏序列及成因机理模式。

河流相致密储层单砂体精细刻画技术

大安油田红1扶余油层属于超低渗透油层,储层物性差、单井产量低、砂体纵向上2~4层,平面上变化快不连续,因此优选有效储层是效益开发的关键。本文针对物性差的特点,明确储层微观与宏观响应性,提取有效储层渗透率及渗砂体厚度,定量刻画渗透性砂体平面展布,结合单砂体刻画明确有效储层分布范围,为区块规模动用提供有效技术手段,并对其他低渗透油田开发具有很好的指导意义。

穿黄探洞2号支洞涌砂来源的研究

一、概况 南水北调东线工程实施的关键是穿黄隧洞的开凿。穿黄隧洞位于山东省东平县与东阿县交界处的关山与位山之间,在自然地理位置上地处鲁西北山地与华北平原的接壤地带,除少量的基岩弧山残丘之外,大面积为厚20—50m的黄河淤积物。

鄂尔多斯盆地塔巴庙地区断层对上古生界天然气富集成藏的控制

为了确定断层对鄂尔多斯盆地塔巴庙地区上古生界天然气富集成藏的控制作用,利用2 000km2高精度三维地震资料,进行断层的精细解释及山西组、太原组煤系地层均方根振幅地震属性的提取,分析断层的分布、成因及形成期,研究断层与天然气高产层段和富集区的关系,建立塔巴庙气田天然气成藏模式。结果表明:上古生界存在北东向断裂系统,断层多为高角度的小断距断层,断距20～60m;这些断层主要是基底断裂在燕山运动中、晚期重新活动造成上覆沉积盖层撕裂形成的;断层形成期与烃源岩生排烃期良好匹配,断层沟通了石炭系太原组、二叠系山西组煤系烃源岩和二叠系下石盒子组盒2段、盒3段岩性圈闭,既促使下伏天然气向盒2段、盒3段垂向汇流运移,同时又为有机酸的运移溶蚀提供通道,有效改善了邻近低渗砂体储层的孔渗性能,从而控制了塔巴庙地区主力目的层盒2段、盒3段天然气运聚成藏及高产富集区带的分布;断裂和大面积相对高孔渗砂体的叠合区域是天然气的有利富集区。

A novel model for assessing the pore structure of tight sands and its application

Pore-structure poses great influence on the permeability and electrical property of tight sand reservoirs and is critical to the petrophysical research of such reservoirs.The uncertainty of permeability for tight sands is very common and the relationship between pore- structure and electrical property is often unclear.We propose a new parameterδ,integrating porosity,maximum radius of connected pore-throats,and sorting degree,for investigating the permeability and electrical properties of tight sands.Core data and wireline log analyses show that this newδcan be used to accurately predict the tight sands permeability and has a close relation with electrical parameters,allowing the estimation of formation factor F and cementation exponent m.The normalization of the resistivity difference caused by the pore- structure is used to highlight the influence of fluid type on Rt,enhancing the coincidence rate in the Pickett crossplot significantly.

油气输导体系研究现状及存在问题的探讨

油气输导体系是油气成藏体系的必要元素,也是油气运移研究的薄弱环节。人们对于这一概念的阐述各不相同,绝大多数学者将其划分为高孔渗砂体、断层及裂缝、不整合面以及它们两两或全部的复合输导体系四种类型,目前对输导体系的研究也集中在这四种类型上。对高孔渗砂体的研究主要集中在孔隙结构、渗透率和优势运移通道上;对断层的研究主要集中在断层泥、非渗透性物质、两盘特征、断层面应力及断层活动性上;对不整合面的研究主要集中在其产状、性质、类型及岩性组合等方面。输导体系的类型划分应当以渗透率非均质性为依据,同时充分考虑烃源岩。从盆地沉积演化的角度出发研究各类输导体系的分布,也是油气运移研究领域中的薄弱环节。

The Unsaturated Hydraulic Parameters for Aeolian Sand

The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten formula and the parameters that characterized the prosperities of aeolian sand such as the unsaturated infiltration coefficient and specific water capacity were obtained.The results showed that the water characteristic curve for aeolian sand in wetting process had greater hysteresis quality than ...

Nuclear magnetic resonance T_2 spectrum:multifractal characteristics and pore structure evaluation

Pore structure characteristics are important to oil and gas exploration in complex low-permeability reservoirs. Using multifractal theory and nuclear magnetic resonance （NMR）, we studied the pore structure of low-permeability sandstone rocks from the 4th Member （Es4） of the Shahejie Formation in the south slope of the Dongying Sag. We used the existing pore structure data from petrophysics, core slices, and mercury injection tests to classify the pore structure into three categories and five subcategories. Then, the T2 spectra of samples with different pore structures were interpolated, and the one- and three-dimensional fractal dimensions and the multifractal spectrum were obtained. Parameters a （intensity of singularity） andf（a） （density of distribution） were extracted from the multifractal spectra. The differences in the three fractal dimensions suggest that the pore structure types correlate with a andf（a）. The results calculated based on the multifractal spectrum is consistent with that of the core slices and mercury injection. Finally, the proposed method was applied to an actual logging profile to evaluate the pore structure of low-permeability sandstone reservoirs.

Simultaneous hydraulic fracturing of ultra-low permeability sandstone reservoirs in China: Mechanism and its field test

Based on the impact of the stress perturbation effect created by simultaneous propagation of multiple fractures in the process of simultaneous hydraulic fracturing, a thorough research on the mechanism and adaptation of simultaneous fracturing of double horizontal wells in ultra-low permeability sandstone reservoirs was conducted by taking two adjacent horizontal wells(well Yangping-1 and well Yangping-2 located in Longdong area of China Changqing Oilfield) as field test wells. And simultaneous fracturing optimal design of two adjacent horizontal wells was finished and employed in field test. Micro-seismic monitoring analysis of fracture propagation during the stimulation treatment shows that hydraulic fractures present a pattern of complicated network expansion, and the well test data after fracturing show that the daily production of well Yangping-1 and well Yangping-2 reach105.8 t/d and 87.6 t/d, which are approximately 9.4 times and 7.8 times the daily production of a fractured vertical well in the same area, respectively. Field test reflects that simultaneous hydraulic fracturing of two adjacent horizontal wells can enlarge the expansion area of hydraulic fractures to obtain a lager drainage area and realize the full stimulation of ultra-low permeability sandstone reservoirs in China Changqing oilfield. Therefore, simultaneous fracturing of two adjacent horizontal wells provides a good opportunity in stimulation techniques for the efficient development of ultra-low permeability reservoirs in China Changqing oilfield,and it has great popularization value and can provide a new avenue for the application of stimulation techniques in ultra-low permeability reservoirs in China.

Determination of microscopic waterflooding characteristics and influence factors in ultra-low permeability sandstone reservoir

Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of Chang 8 ultra-low permeability sandstone reservoir of Upper Triassic Yanchang formation in Huaqing region of the Ordos Basin,China is difficult to observe directly.Combined with physical property,casting thin sections,constant-rate mercury injection capillary pressure and nuclear magnetic resonance,the influence of reservoir property on the waterflooding characteristics in pores were analyzed and evaluated.Seepage paths of waterflooding characteristics were divided into four types:homogeneous seepage,reticular-homogeneous seepage,finger-reticular seepage and finger-like seepage,the waterflooding efficiency of which decreases in turn.More than 70%of residual oil occurs as flowing-around seepage and oil film.Physical property,pore structure and movable fluid characteristics are all controlled by digenesis and their impacts on waterflooding efficiency are in accordance.Generally,the pore throat radius size and distribution and movable fluid percentage are closely related to waterflooding law.

Experimental research on seismoelectric effects in sandstone

The seismoelectric effects induced from the coupling of the seismic wave field and the electromagnetic field depend on the physical properties of the reservoir rocks. We built an experimental apparatus to measure the seismoelectric effects in saturated sandstone samples. We recorded the seismoelectric signals induced by P-waves and studied the attenuation of the seismoelectric signals induced at the sandstone interface. The analysis of the seismoelectric effects suggests that the minimization of the potential difference between the reference potential and the baseline potential of the seismoelectric disturbance area is critical to the accuracy of the seismoelectric measurements and greatly improves the detectability of the seismoelectric signals. The experimental results confirmed that the seismoelectric coupling of the seismic wave field and the electromagnetic field is induced when seismic wave propagating in a fluid-saturated porous medium. The amplitudes of the seismoelectric signals decrease linearly with increasing distance between the source and the interface, and decay exponentially with increasing distance between the receiver and the interface. The seismoelectric response of sandstone samples with different permeabilities suggests that the seismoelectric response is directly related to permeability, which should help obtaining the permeability of reservoirs in the future.

Model building for Chang-8 low permeability sandstone reservoir in the Yanchang formation of the Xifeng oil field

In order to build a model for the Chang-8 low permeability sandstone reservoir in the Yanchang formation of the Xifeng oil field,we studied sedimentation and diagenesis of sandstone and analyzed major factors controlling this low permeability reservoir.By doing so,we have made clear that the spatial distribution of reservoir attribute parameters is controlled by the spatial distribution of various kinds of sandstone bodies.By taking advantage of many coring wells and high quality logging data,we used regression analysis for a single well with geological conditions as constraints,to build the interpretation model for logging data and to calculate attribute parameters for a single well,which ensured accuracy of the 1-D vertical model.On this basis,we built a litho-facies model to replace the sedimentary facies model.In addition,we also built a porosity model by using a sequential Gaussian simulation with the lithofacies model as the constraint.In the end,we built a permeability model by using Markov-Bayes simula-tion,with the porosity attribute as the covariate.The results show that the permeability model reflects very well the relative differences between low permeability values,which is of great importance for locating high permeability zones and forecasting zones favorable for exploration and exploitation.