超高压气藏渗流机理及气井生产动态特征

超高压气藏渗流机理不同于常规气藏,认识此类气藏开发机理,搞清气藏开采规律,是科学高效开发该类气田的关键。针对川东北地区碳酸盐岩超高压气藏地质条件,通过应力敏感实验研究了该类气藏开采过程中岩石的变形特征,确定了储层孔隙度、渗透率等参数随压力的变化关系;在此基础上,建立了考虑储层裂缝和基质变形、高速非达西流动的碳酸盐岩超高压气藏气、水两相渗流数学模型和数值模型,利用该模型研究了气井开采动态特征。研究表明:超高压碳酸盐岩气藏储层渗透率应力敏感性很强,渗透率随有效应力增加表现为明显的3段,有效应力增加小于20MPa前渗透率急剧降低,下降幅度达45%~65%;有效应力增加介于20~60MPa之间时渗透率下降幅度为20%~25%;有效应力增加大于60MPa后,渗透率基本不变;储层孔隙度对应力的敏感性小,当有效应力增加40MPa时,孔隙度损失小于10%;孔隙度和渗透率越小,岩石应力敏感性越强;岩石变形对裂缝—孔隙型超高压碳酸盐岩气藏生产影响明显,气井初期配产不能太大;建立的考虑岩石变形、高速非达西的双重介质模型能准确预测碳酸盐岩超高压气藏的开采动态。     

砂岩气藏衰竭开采过程中含水饱和度变化规律

基于四川须家河组气藏典型储集层物性特征,选择了渗透率分别为1.630×10-3μm2、0.580×10-3μm2、0.175×10-3μm2、0.063×10-3μm2的4组砂岩岩心,模拟研究含水砂岩气藏衰竭开采过程中(地层压力从20 MPa衰竭开采至废弃)含水饱和度沿程变化规律,结合岩石微观孔喉结构与毛管压力特征,分析了不同渗透率砂岩与水相的相互作用机理并由须家河组气藏2口井进行验证。研究表明:1砂岩储集层对水相捕集作用的大小与渗透率关系密切,储集层渗透率临界值为(0.175~0.580)×10-3μm2;2渗透率大于0.580×10-3μm2的储集层,岩石孔喉半径较大,毛管压力较小,岩石孔喉对水相的捕集作用小,孔隙内的一部分水在气相驱替作用下可以被驱替出来成为可动水;3渗透率小于0.175×10-3μm2的致密储集层,其孔喉细小,毛管压力较大,岩石孔喉对水相的捕集作用强,在气相驱替作用下,水相难以被驱替出来而滞留在岩石孔喉内,造成含水饱和度不降反升,因此对此类储集层,要严格控制合理生产压差,延长气井生命周期。图7表2参10     

高压—超高压碳酸盐岩气藏渗流机理及开发特征——以阿姆河盆地M区为例

为了弄清影响高压—超高压气井生产动态的根本原因,选取土库曼斯坦阿姆河盆地M区多个碳酸盐岩气藏储层岩心,开展了多回次变围压应力敏感、衰竭式开发、CT扫描及三维数字岩心模拟等实验,在此基础上,深入剖析了高压—超高压气井的生产动态特征,研究了不同产状裂缝及其发育程度对气井产能的影响,进而提出了M区高压—超高压碳酸盐岩气藏在开发早期需采取的合理对策。研究结果表明:(1)应力敏感实验表明,孔隙型及孔洞型岩心应力敏感程度中等偏弱,裂缝—孔隙型岩心应力敏感程度强,渗透率不可逆损害率高且损害率主要集中在加压初期;(2)岩石弹性膨胀是高压—超高压气藏开采早期的主要驱动能量;(3)高压—超高压气藏在开发早期应控制采气速度,有利于降低气井产能递减幅度、增加阶段采出程度;(4)裂缝—孔隙型储层中气井初始产能主要受裂缝发育程度的影响,产能递减幅度主要受裂缝产状的影响;(5)以发育低角度裂缝为主的储层,地层压力降低后裂缝易闭合,气井产能递减较快,在开发早期应严格控制生产压差;(6)阿姆河盆地高压—超高压气藏大部分气井在地层压力降至45 MPa以前,应尽量保持生产压差小于5 MPa。结论认为,所建立的方法具有一定的通用性,可以为其他地区高压—超高压气藏的优化开发提供借鉴。     

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研究了川中充西地区香四段储层的孔隙类型、孔隙度、渗透率、含水饱合度等特征,表明该层具有产气能力。岩心产能全模拟试验表明,当生产压差为6 MPa时,香四段气藏可达到0.5×104 m3/d工业产气标准,当生产压差增至10 MPa时,单井产量可达到（2.5~3.0）×104 m3/d,为一低产能气藏。动态损害模拟表明产层已受到损害,单井产量损害了25%~50%;开井生产初期气相渗透率大于0.2×10-3μm2,产水时气相渗透率小于0.05×10-3μm2,生产中可产出少量原生水,研究结果与该区测试资料基本吻合。     

低渗气田复合压裂工艺技术

1 白庙气田概况白庙气田原始天然气地质储量 10 7× 10 8m3 ,凝析油地质储量 15 8× 10 4t,气层埋深 2 6 30～ 4 0 90m ,砂岩气层孔隙度6 1%～ 15 5 % ,其中 84 %的层孔隙小于 15 % ,渗透率 0 1～ 12× 10 -3 μm2 。气藏温度 89 8～ 14 3 0℃ ,压裂系数 0 98～1 75 ,原始地层压力 2 5 74～ 71 38MPa。相对密度 0 5 913～0 6 913,凝析油相对密度 0 73～ 0 82mg/L ,地下粘度 0 5 3～ 8 5 4mPa·s .地层水pH值 5 4～ 6 2 ,相对密度 1 0 5～1 12 ,水型为CaCl2 型 ,总矿化度 6 8～ 17 5× 10 4mg/L。砂岩储层酸敏、水敏、速敏…     

河坝飞仙关气藏储层应力敏感性及其对产能的影响

河坝飞仙关气藏是一个裂缝孔隙型异常高压气藏,地层压力系数高达2.3。试采过程中,气井产能下降明显,表现出一定的应力敏感。通过对河坝飞仙关气藏储层岩石渗透率应力敏感、压差对渗透率应力敏感影响、渗透率可恢复性等室内岩心试验研究,结果表明:河坝飞仙关气藏储层渗透率敏感性强,渗透率损害率高达60%;渗透率永久性变形率较大,可恢复程度低;压差对渗透率敏感影响大,压差越大,渗透率敏感性越强,永久变形率越大。结合现场生产分析表明:应力敏感对河坝飞仙关气藏开发的影响大,气井产能下降快,地层压力降到20MPa时,产能下降了66%;对于河坝异常高压气藏开发,确立合理生产压差,减缓应力敏感对储层渗透率及气藏产能的损害,确保气藏在合理生产压差及合理产量下生产十分必要。     

川东北碳酸盐岩气藏岩石渗透率变化实验

地应力变化是一个三轴方向上的综合应力变化,传统的应力敏感性实验与地层真实情况存在较大误差。为了研究超高压碳酸盐岩气藏储层渗透率与有效应力的关系,针对实际井获取的岩心,设计了不考虑岩石中孔隙流体压力的三轴应力变形实验和考虑岩石中流体压力的变形实验方案,推导了由三轴应力实验数据计算渗透率变化的数学模型,在此基础上分析了川东北碳酸盐岩超高压气藏岩石渗透率变化与有效应力的关系。结果表明:在同样的有效应力条件下,考虑孔隙中流体压力时渗透率下降幅度更大。3号岩心有效应力达到50 MPa时,无因次渗透率下降幅度为57.48%。对于天然裂缝发育的岩心,使用考虑岩心中流体压力的变形实验能更好地获取渗透率的变化规律;对于天然裂缝不发育的岩心,使用不考虑岩心中孔隙流体压力的三轴应力实验能更好的获取基质渗透率的变化规律。对比国内外异常高压气藏,认为研究区气藏渗透率的应力敏感性较强。实验研究为气藏科学、高效开发提供了科学保障。     

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平落坝须二气藏属断层—构造圈闭类型边水气藏。气藏原始地层压力 42 1 56MPa ,地层温度1 0 0 1 6℃ ;储层埋深 341 9 0 0～ 3845 0 0m ;岩性为细—中粒长石石英砂岩及岩屑砂岩和长石砂岩 ;储层基质物性 ,岩心分析平均孔隙度为 3 42 % ,平均渗透率为 0 1 61 8× 1 0 - 3μm2 ,非均质系数为 44 1 4～ 494 53;裂缝发育 ,试井解释结果 ,渗透率是岩心渗透率的 54 56～ 2 0 72 77倍 ,属孔隙—裂缝型储层。须二气藏自 1 990年开采以来 ,经多项综合研究和开采证实 ,须二气藏为统一的水动力系统 ,且边水不活跃 ,气井原始地层压力具有先期压降特征 ,且连通性很好。天然气中甲烷 96 0 %～ 97 0 % ,相对密度为 0 570～ 0 575,气质好 ,不含硫化氢 ,天然气储量为数百亿立方米 ,采用多种方法计算结果 ,天然气储量数值相对误差仅 0 2 9%。根据现有的 1 1口生产气井 ,经多次试井测试及生产证实 ,天然气产能较高。须二气藏天然气储量及储量丰度是四川盆地目前天然气储量大、储量丰度高的天然气藏之一。     

青西油田下白垩统下沟组储集层特征

青西油田下白垩统下沟组(K1g)为深层裂缝-孔隙型砾岩储集层,油藏埋深4200～4600m,基质孔隙度小于8%,基质渗透率小于1×10-3μm2.由于砾岩储集层内高角度裂缝发育,改善了它的渗流性能。针对这类低孔、低渗透储集层,通过岩石成分、孔隙类型及组合、孔隙结构、核磁共振、测井评价及测试等技术,并结合裂缝平面预测结果,进行储集层预测,取得了良好的效果。     

提高缝洞型气藏采出程度的物理实验——以高磨地区震旦系灯影组气藏为例

高磨地区震旦系缝洞型气藏孔隙、溶洞、裂缝搭配关系复杂,储层渗流能力的较大差异导致难以准确预测气藏的采出程度。为认识并量化储层非均质性对储量可采性的影响,开展地层条件下各类储层岩心的串、并联衰竭式开发实验。通过改变实验压差和岩心的组合方式,明确流量与压力随时间的变化关系,评价现有工艺技术条件下储层类型、生产制度对气藏采出程度的影响。串联实验中,气体流动路径为孔隙→孔洞→裂缝-孔洞时,岩心采出程度最大;气体流动路径为孔洞→裂缝-孔洞→孔隙时,采出程度减少14%。并联实验中,实验压差5 MPa时最终累计产气量最大,但由于高渗岩心孔隙压力下降过快,后期累产气量增加幅度减小;实验压差3 MPa时,各类岩心同时供气的时间延长,实现了"动态供给平衡",累产气量增加幅度保持稳定。该实验研究从微观上认识了不同类型储层组合下的产量贡献特征,量化了低渗储层对高渗储层的制约性,对缝洞型气藏早期开发对策的制定具有指导意义。     

阿姆河右岸酸性气田井口冲蚀及对策

中亚土库曼斯坦阿姆河右岸气田群为高含H_2S和CO_2的碳酸盐岩气藏,单井产量高,井口设备均出现了不同程度的腐蚀。初步分析认为其原因是生产过程中仅考虑酸性介质对气井井口的化学腐蚀,而没有考虑气体流速对井口的冲蚀作用,极大地影响了气田的安全生产。为此,通过对节流阀上下游阀道、法兰面均出现明显坑状腐蚀的进一步分析,明确了化学腐蚀和气体冲蚀的交互作用是井口磨损的主要影响因素,气流冲刷腐蚀坑的化学腐蚀产物会加速冲蚀损害;进而借鉴冲蚀与腐蚀运行环境下的多相管流管道的磨损计算理论,计算了该运行环境下的冲蚀极限速度,得到了不同生产工况下节流阀的抗冲蚀流量;最后,根据气田生产情况,针对性地提出了按气井配产要求来选择采气树类型、节流阀通径及类型冲蚀的技术控制策略。此举为气田安全生产提供了工程技术保障。     

山前地区深井超深井套管防磨与减磨技术研究

针对山前地区深井超深井钻井过程中套管磨损严重的问题,在分析套管磨损机理的基础上,开展了山前地区套管防磨与减磨技术研究,基于技术研究成果及应用实践,得到如下结论:1应用Power V等垂直钻井系统控制井眼轨迹,特别是上部井段的狗腿度和井斜,可明显减小侧向力和磨损量,缩短套管磨损时间;2应综合考虑套管磨损率、磨损系数以及钻杆耐磨带本身的磨损量,优选出效果最优的耐磨带;在狗腿度严重的位置,可考虑采用一定数量的橡胶钻杆卡箍来减轻对套管的磨损;3山前地区钻井液采用CX-300减磨剂能够显著降低磨损速率,减轻套管磨损程度,但在不同钻井液体系使用之前应进行优化分析以确定最佳使用量;4在迪那204井使用高密度钻井液体系,全部采用优选的高密度重晶石粉代替铁矿粉作为加重剂,整个钻进过程中未出现钻具及套管磨损,迪那204井易损件消耗量仅为邻井迪那203井的左右,防磨减磨效果非常显著。     

Biodiesel Projects Helpful to Ease Energy Shortage

Nearly 7,000 hectares of biodiesel forest will take shape in the northern province of Hebei in 2008, part of a national campaign to fuel the fast growing economy in a green way. In no more than five years, the Pistacia chinensis Bunge, whose seeds have an oil content of up to 40 percent, will yield five tons of fruit and contribute about two tons of high-quality biological diesel oil, according to the provincial forestry administration.     

State Energy Base Proposed in Inner Mongolia

Experts recently suggested China set up a state energy base in lnner Mongolia Autonomous Region to ease its energy thirst. The survey was co-conducted by senior researchers from the National Development and Reform Commission, Development Research Center of the State Council, Chinese Academy of Sciences and the Ministry of Finance. To plan and establish strategic energy bases at state level is in line with the principle of ＂giving priority to energy saving and diversifying energy consumption with the utility of coal at the core.＂     

Influence of Shale Oil Boom in North America upon nternational Crude Price Flucturation

正Current stituation of shale oil development in the world The US The country is blessed with abundant shale oil resources and had matersed whole sets of theories and technologies needed for their exploration and development after years of practices.According to an assessment of shale oil resources in major countries and regions of the world issued by the U.S.Energy Information Agency(EIA),the US ranks the second in the world with its 6.8 billion tons of technically recoverable shale oil(shale oil in place is about 136.3 tons).About 8plays had been confirmed to have     

A Sintering-resistant Pd/C Composite Catalyst for Ethylbenzene DehydrogenationDeveloped by CAS Institute of Metals

Carbon deposition is a commonplace phenomenon occurringin the catalytic reaction process, in particular inthe system of direct dehydrogenation of ethylbenzene,because the reactant - ethylbenzene molecules on thesurface of metal oxide catalysts are prone to quickly formcarbon deposits, leading to deactivation of catalysts. Recently,the associate research fellow Mr. Liu Hongyangand the research fellow Mr. Su Dangsheng of the StateShenyang Material Science （United ） Laboratory of theInstitute of Metal Research, CAS by taking advantageof the carbon deposition process during direct dehydrogenationof ethylbenzene have ingeniously designeda Pd/C composite catalyst. This catalyst in comparisonwith the traditional commercial carbon nanotubesupported Pd catalyst shows a significantly improved performancein terms of its catalytic activity and sinteringresistantability.     

ZPEB Overseas Markets Keep Steady and Efficient Development

In recent years, Zhongyuan Petroleum Exploration Bureau （ZPEB） has made rapid development in overseas petroleum markets through its integrated reorganization. A new international business plattbrm established, aimed at becoming a highly ranked contractor with international petroleum engineering technology. ZPEB has expanded its business scope and scale, regulated the market structure,     

New Era for China-Brazil Relations

China and Brazil celebrated the 40th anniversary of establishing diplomatic relations between the two countries in July this year. Bilateral relations between China and Brazil have entered a new stage, and experts expect the already extensive cooperation between the two countries to deepen and broaden as Chinese President Xi Jinping made a state visit to Brazil in mid-July, which is his first state visit to Brazil since he assumed the office last year. The visit to China＇s largest trade partner in Latin America is at the invitation of Brazilian President Dilma Rousseff.     

Large Scale Ethylene Production Package Technology SuccessfullyDeveloped by CNPC

The CNPC Group has successfully developed a largescaleethylene production package technology with independentintellectual property rights, which has beensuccessfully applied in the 1.2 Mt/a ethylene revamp andexpansion project at the Daqing Petrochemical Complex（DPC）.     

Recent Advancements in Petroleum E & P Equipments in China

The role of equipments in oil and gas exploration and development had never been attached with so much importance as that in shale oil and gas boom in the U.S. With the help of massive hydraulic fracturing and horizontal drilling techniques, the U.S., the world＇s No. 1 oil importer even started to dream about energy self-sufficiency with its proudly high production of shale oil and gas from several major shale plays in the country. However, what behind this remarkable achievement are powerful multi-stage hydraulic fracturing machinery and smart tools for directional drilling.