苏里格气田苏77区块丛式井优快钻井配套技术

苏77区块处于生态环境脆弱的半沙漠半草原地区,采用丛式井开发方式,不仅可以加快产能建设,而且可以降低钻井成本,保护环境,便于气田维护管理。针对苏77区块钻井存在的技术难点,根据地层自然增降斜及方位漂移规律,从平台部署、井身轨迹剖面、钻具组合、PDC钻头选型及钻井液体系及性能维护等方面进行优化,形成了一套适应苏77区块的丛式井优快钻井配套技术,有效地提高了机械钻速,缩短了钻井周期及平台建井周期,加快了产能建设。其中,苏77-6-5井完钻井深3167 m,钻井周期仅为9.98天,创造了整个苏里格气田定向井最短钻井周期记录。     

苏里格气田西区低阻气层成因分析

苏里格气田西区上古生界二叠系的主要含气目的层为盒8段及山1段,而此区域高阻气层与低阻气层共存,运用电阻率难以区分气层与水层,这给测井评价带来很大难度。因此正确认识低阻气层的成因,对准确识别储层中流体类型十分重要。本次研究从沉积背景、储层岩性、储层物性和钻井工程的角度出发,对低阻气层的成因和特点进行了分析,认为粘土矿物分布,泥浆滤液侵入是造成气层低阻的主要因素,而高不动水饱和度是引起该区气层低阻的最主要原因。另外高地层水矿化度,也是造成该区低阻的成因。通过此次研究,其成果可为该区低阻气层的正确识别和评价提供重要依据。     

苏里格东区召51-统41井区储层特征及影响因素

苏里格东区召51-统41井区气藏为典型的岩性气藏,主要勘探层位是盒8段、山1段。通过对岩心、铸体薄片、扫描电镜及物性资料的分析,对该区储层岩石学特征、孔隙类型、储层物性及其影响因素进行了研究。结果表明：该区储层岩石类型主要为岩屑砂岩、岩屑石英砂岩;储层为孔隙型储层,孔隙以残余粒间孔、溶蚀孔、晶间孔为主;孔隙结构具有中一小孔喉、分选中等、排驱压力高和主贡献喉道小的特点;同时储层具有低孔、低渗的特点。沉积环境和成岩作用是影响储层物性的主要因素。     

A Volumetric Model for Evaluating Tight Sandstone Gas Reserves in the Permian Sulige Gas Field,Ordos Basin,Central China

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.     

致密砂岩储层孔喉结构差异对可动流体赋存特征的影响——以苏里格气田东区和西区盒8储层为例

为探讨致密砂岩储层的微观孔喉结构参数对可动流体赋存特征的影响,本文以苏里格气田东区和西区盒8储层为例,利用铸体薄片、扫描电镜、恒速压汞及核磁共振等实验方法,对比并分析了微观孔喉结构差异对可动流体赋存特征的影响。结果表明:喉道大小及分布特征是造成致密砂岩储层渗流能力不同的主要因素,喉道半径分布范围越宽,峰值越大,渗流能力就越强;相反,喉道半径分布范围越窄,峰值越小,渗流能力就越弱。致密砂岩储层在可动流体赋存特征方面的差异本质是源于喉道发育程度不同,特别是在孔喉结构非均质性越强的储层中,喉道对可动流体的赋存特征影响越为显著。致密砂岩储层的有效孔隙体积相比于有效喉道体积对可动流体的影响更大,也更能表征流体的赋存状态。     

苏里格气田西区盒8下亚段辫状河沉积论证与分析

鄂尔多斯盆地苏里格气田西区盒₈^下亚段主力含气层段相的研究观点较多,不同认识导致各个沉积相域内砂体对比和预测存在着较大的差异,从而给勘探井位部署增加了难度。笔者在前人研究成果基础上,充分利用钻井、测井、岩心、地震、分析化验和野外露头等多种资料和手段,采用岩石学特征分析、岩心沉积构特征观察、古生物化石证据、研究区柳林成家庄野外露头沉积序列揭示、测井相特征和河流相地震特殊反射结构观察等多种研究手段和方法,对该区盒₈^下亚段的沉积相进行了详细论证、分析和描述。研究结果表明,辫状河沉积是苏里格西区盒₈^下亚段主要的相类型;干旱与潮湿气候的频繁交替变化,是导致砂体研究区目的层垂向砂体厚度大、非均质性强和砂体横向变化快的主控因素。     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly,namely regional caprock of upper mudstone,middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone,glutenite and the Ordovician carbonate buried hill.Natural gas in Hetianhe gasfield sourced from the Cambrian source rock.It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases,while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases.Natural gas is rich in H2S and accumulated in multiply stages as the result of TSR.The accumulation history is divided into three stages,namely accumulation and breakage in the late Caledonian-early Hercynian,migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

关于苏里格气田东二区盒8段储层成岩相的再认识

成岩相作为油气勘探过程中的热门方法,其定义的不同造成研究成果的差异。前期通过对苏里格气田东二区盒8段储层岩石学和成岩作用的详细研究,按照邹才能等(2008)提出的成岩相分类和命名原则,将研究区盒8段储层划分为五种成岩相。此次研究结合流体包裹体的分析测试结果,对研究区盒8段储层的成岩环境进行了分析,并利用成岩环境对其成岩相进行了再研究,在原研究程度的基础上完善了成岩相的形成过程和形成阶段。研究区盒8段储层在成岩过程中经历了淡水-弱酸性的大气成岩环境、弱酸性-酸性的埋藏成岩环境和弱碱性的埋藏成岩环境。受成岩环境的影响,形成了不同的成岩相:同生成岩-早成岩A早期受大气淡水、弱酸性埋藏成岩环境的影响,主要发生压实、弱酸性溶蚀作用形成弱溶蚀-压实相;早成岩A晚期-早成岩B期受弱酸性埋藏成岩环境的影响,压实作用与酸性溶蚀作用持续增强,形成溶蚀-压实相;中成岩A期-中成岩B早期为酸性埋藏成岩环境,广泛产生胶结作用与酸性溶蚀作用,形成溶蚀-胶结相;中成岩B晚期表现为碱性埋藏成岩环境,主要发生碱性交代作用,形成交代相。根据储层成岩相的影响因素:岩性、成岩环境、成岩作用类型和孔隙结构特征,按照"成岩相是成岩环境的物质表现"的定义,提出采用"岩性+成岩环境+(孔渗级别)+主要成岩作用"的命名方法,将苏里格气田东二区盒8段储层成岩相划分为五种类型:中细粒(杂)砂岩大气环境致密压实相;净砂岩大气、酸性埋藏环境特低孔渗溶蚀-压实相;净砂岩酸性埋藏环境低孔渗溶蚀相;净砂岩酸性埋藏环境特低孔渗溶蚀-胶结相以及净砂岩碱性埋藏环境致密交代相。     

鄂尔多斯盆地苏里格气田西南部致密储层非均质性特征及对成藏的制约

致密砂岩气藏是我国非常规油气资源的重要组成,其储层非均质性严重影响了致密气成藏和甜点区优选,进而制约了气田高效开发。为进一步揭示储层非均质性成因及对致密气成藏的影响,选取鄂尔多斯盆地苏里格气田西南部山1段和盒8段致密储层为例,通过岩芯观察、扫描电镜、薄片鉴定、生产和测井分析等技术手段,研究储层非均质特征,探讨沉积作用和微观孔隙演化对非均质性和成藏的影响。结果表明,储层非均质性多表现为层内粒度的垂向韵律性、夹层的不均匀分布、渗透率的平面分布差异等;储层非均质性受沉积作用和成岩作用共同影响,沉积作用控制了水动力条件、砂体展布、厚度和砂体构型,储层微观非均质性受岩矿组构和孔隙演化影响;不同厚度和构型的复合砂体,多样的矿物组分、孔隙结构,致密气的选择性充注,共同造成了苏里格地区致密储层的非均质性及含气性差异。复合砂体的高孔渗部位是致密气开采的甜点区,但是在优选有利区时不应只关注这些厚层的高孔渗砂体,也应关注规模小、非均质性稍强的透镜状砂体,需要充分考虑到储层非均质性对致密气成藏的影响。