Most reservoirs of the Middle Permian Maokou Formation in central Sichuan Basin are extended in Maokou 2 Member.They feature complex lithology,well-developed fractures and vugs,and strong heterogeneity,leading to challenges in identifying and evaluating them and their effectiveness through well logging.Dependent on one single index of storage coefficient,the past effective-ness evaluation might create the mismatch of productivity with reservoir parameters.So,some logging data of the Maokou Formation was re-evaluated for 300-plus wells in central basin.The effectiveness as one single index with the other four factors were analyzed in-dividually,including dolomite development degree,reservoir storability and permeability,and fracture or vug development degree.Af-ter that,the indicator was constructed for reservoirs to characterize their comprehensive quality.Coupling with the thicknesses of clas-sified reservoirs,the coefficient of comprehensive quality was determined to correlate with the tested productivity.Results show that(i)because one single parameter based on logging evaluation cannot achieve an accurate effectiveness,a multi-factor model should be built for the comprehensive quality by taking lithology,storability and permeability into account;and(ii)considering that larger thick-nesses of reservoirs and Class I + II reservoirs correspond to higher tested productivity,the thickness of classified reservoirs can be combined to determine,which helps improve an accuracy to predict the productivity.By using this prediction model established,some potential reservoirs may be optimized,and one testing suggestion for old wells is also proposed.These findings effectively support not only the improvement of both reserves and production but the optimization of target zones in the Middle Permian Maokou Formation of central Sichuan Basin.

四川盆地侏罗系大安寨段页岩有机碳(TOC)含量高,厚度较大,物性与含油气性均较好,开发潜力巨大,但在常规油气储层和海相页岩气储层研究中形成的孔隙度、TOC含量等关键参数计算方法和测井评价标准在该段页岩油气评价中并不适用.以岩石物理实验分析为基础,将自然伽马测井、声波时差测井和电阻率等常规测井与核磁共振、岩性扫描等测井等新技术相结合,建立了川中大安寨段页岩油气储层TOC含量、孔隙度、含气饱和度、游离烃(S1)含量等关键参数的计算模型,形成了大安寨段页岩油气储层评价指标体系,模型计算结果与岩心分析结果吻合较好,经生产实践证明该项技术应用效果明显.该研究成果能够有效地支撑四川盆地页岩油气储层的"甜点"选区、井位部署和老井上试方案优选.

近年在川西地区泥盆系观雾山组见到了较好的储层分布,多口井获得工业气流.然而,川西观雾山组岩心缝洞中沥青充填严重,储层沥青含量和储层参数定量计算难度大.为此,从沥青对观雾山组储层定量影响分析入手,通过高温循环沥青溶解实验建立沥青溶解前后的孔隙度—声波时差、孔隙度—电阻率模型,采用纵波时差—横波时差、声波时差—电阻率等模型定量计算沥青含量,进而得到沥青校正后的储层参数.结果表明:①沥青占据着储集层的部分储集空间,不仅减小储集层的孔隙度,还大大降低储集层的渗透性,严重影响了储集层的物性及产能;②通过沥青对各类测井参数影响分析发现,沥青对储集层物性、岩样密度、声波时差以及电阻率均具有一定的影响,并且随着沥青含量的增多,影响越大,尤其是横波时差和电阻率;③经岩心资料验证,经沥青校正后测井评价结果可靠,效果较好,可有效指导测井采集系列优化及试气选层,为气藏井位部署提供依据.

近年,不断发现新的火成岩油气藏,其勘探潜力巨大.但是火成岩岩性复杂,储层多为溶蚀孔洞—裂缝双重孔隙介质的强烈非均质储层,其岩性测井识别与储层测井评价都非常困难.为此,以准噶尔盆地东部石炭系火成岩为例:①针对岩性复杂多样,岩性识别敏感参数不清的问题,利用主成分分析方法确定该区块的火成岩岩性敏感曲线为密度、电阻率和自然伽马,并在此基础上建立了三维岩性识别图版;②针对物性解释精度低,基质孔隙度计算采用岩心刻度测井曲线的方法,分岩性建立了物性解释模型;③采用建立成像测井与双侧向测井相关性的方法来表征裂缝孔隙度.结果表明:①三维岩性图版比二维图版增加1个参数,更适合复杂的火成岩岩性解释;②经过岩心刻度分不同岩性建模计算的基质孔隙度符合储量计算的精度要求;③裂缝孔隙度的计算结果表明裂缝发育与岩性有着密切关系,储层主要发育在裂缝孔隙度较高的角砾凝灰岩和火山角砾岩中,安山岩岩性致密,但裂缝较发育,可作为潜力储层.

四川盆地川中地区下二叠统栖霞组天然气勘探获得了重大突破.该区储层以薄层状白云岩为主,孔隙类型多样,孔隙结构复杂,溶蚀孔洞的大小、分布情况都表现出很强的非均质性,大大增加了测井储层综合评价的难度.由于成像测井具有较高纵向分辨率、直观反映井壁孔洞和裂缝等优点,故利用该区丰富的成像测井资料来计算栖霞组地层的孔隙度谱,并将孔隙结构分类,建立成像孔隙度谱图版,然后根据孔隙度谱开展基质孔和次生溶孔的定量计算,并结合常规测井计算的孔隙度,对储层类型进行了划分.结果表明:①成像孔隙度谱结构特征在一定程度上可反映孔径大小的分布情况,进而反映储层孔隙结构特征,不同的谱结构反映不同孔隙类型组合特征和原生孔隙与次生孔隙的搭配关系;②栖霞组孔隙度谱结构可分为无峰宽谱型、多峰中谱型、单峰中谱型和单峰窄谱型4种类型,有利储层的成像孔隙度谱以无峰宽谱型和多峰中谱型为主;③通过标定成像孔隙度谱可定量计算地层基质孔和溶蚀孔的孔隙度,进而划分储层类型.

The Lower Permian is one of the important strata of natural gas exploration and development in Sichuan Basin.There are strong heterogeneity,well logging evaluation,prestack processing and reservoir prediction of fracture cave type reservoirs.Therefore,to carry out research of geophysical technology and the formation of supporting technology,mainly include: first,through in-depth analysis of logging,conventional logging and electric imaging and stone wave logging data,establish reservoir logging response characteristics,grasp the fractured vertical distribution;Second,on the basis of this,put forward the amplitude preserving processing technology in in terms of static correction,SNR,consistency and improve the resolution of seismic data,the high accuracy;through the forward model,establish Maokou reservoir seismic response model,guide the optimization of seismic attributes to carry out cave of prediction;through the prestack stochastic inversion,predict quantitative reservoir.The carbonate fracture cave unit used 3D visualization technology of space carving in the depiction;Cave Automatic Tracking Based on the discrete model for fractured vuggy connectivity is analyzed.The prediction results proved consistence with the actual drilling well,which provide a basis for well deployment,and put forward "go out looking for karst structure",shallow deep to find out the new ideas.It has important guiding significance to deepen the exploration and development of new exploration field expansion of Maokou Formation of complex carbonate gas reservoir.

The detection depth of borehole electrical imaging logging is shallow,so it is hard to determine whether the fractures observed on the image developed away from the wellbore.The fracture strike identified by electrical imaging logging was integrated with the shear wave anisotropy orientation measured by Sonic Scanner logging to carry out modeling.The anisotropy caused by fractures in reservoir and the extension of the fractures in the borehole were determined,and then the effectiveness of fractures was evaluated.This methodology was successfully applied in effectiveness evaluation of fracture-vug carbonate reservoir of Sinian Dengying Formation in Sichuan Basin.The combination of Sonic Scanner logging and electrical imaging logging can accurately evaluate the fracture effectiveness around the wellbore,and it provides a reliable basis for reservoir evaluation and optimization of test interval.

四川盆地川中地区下二叠统茅口组和栖霞组发育裂缝—孔洞型白云岩储层,多口井测试获高产工业气流.但茅口组热次盆相白云岩岩性复杂、富含硅质、非均质性强,测井储层精细评价困难;栖霞组白云岩受岩溶及多期构造作用影响,缝洞发育,储层厚度薄,基质具有低孔隙、低渗透特征,储层评价及产能预测难度大.通过综合分析常规测井、成像测井、阵列声波测井资料,结合地质录井资料,建立白云石、方解石和硅质岩等复杂岩性及非均质构造识别标准,解决了茅口组硅质白云岩岩性识别问题;基于成像裂缝、孔洞参数、斯通利波能量衰减、核磁孔隙结构参数建立了储层定量判别标准及图版.该方法在川中地区下二叠统储层评价中取得了良好的应用效果,测井解释符合率超过80％,为川中地区下二叠统天然气储量申报提供了技术支持,为川中地区高石梯—磨溪—龙女寺地区立体勘探、寻找规模储量与资源接替领域提供了支撑作用.