Formation damage mechanism and control strategy of the compound function of drilling fluid and fracturing fluid in shale reservoirs

For the analysis of the formation damage caused by the compound function of drilling fluid and fracturing fluid,the prediction method for dynamic invasion depth of drilling fluid is developed considering the fracture extension due to shale minerals erosion by oil-based drilling fluid.With the evaluation for the damage of natural and hydraulic fractures caused by mechanical properties weakening of shale fracture surface,fracture closure and rock powder blocking,the formation damage pattern is proposed with consideration of the compound effect of drilling fluid and fracturing fluid.The formation damage mechanism during drilling and completion process in shale reservoir is revealed,and the protection measures are raised.The drilling fluid can deeply invade into the shale formation through natural and induced fractures,erode shale minerals and weaken the mechanical properties of shale during the drilling process.In the process of hydraulic fracturing,the compound effect of drilling fluid and fracturing fluid further weakens the mechanical properties of shale,results in fracture closure and rock powder shedding,and thus induces stress-sensitive damage and solid blocking damage of natural/hydraulic fractures.The damage can yield significant conductivity decrease of fractures,and restrict the high and stable production of shale oil and gas wells.The measures of anti-collapse and anti-blocking to accelerate the drilling of reservoir section,forming chemical membrane to prevent the weakening of the mechanical properties of shale fracture surface,strengthening the plugging of shale fracture and reducing the invasion range of drilling fluid,optimizing fracturing fluid system to protect fracture conductivity are put forward for reservoir protection.

THE RELATIONS BETWEEN DEEP DYNAMIC PROCESS AND THE FORMATION OF OIL-GAS POOLS IN THE SONGLIAO BASIN,CHINA

THE RELATIONS BETWEEN DEEPDYNAMIC PROCESS AND THEFORMATION OF OIL-GAS POOLS INTHE SONGLIAO BASIN, CHINALi Zhi’an(Changsha Institute of Geotectonics, Academia Sinica, Changsha, 410013, Hunan, China)Songliao basin, crust structure, deep dynamics, the formation of oil-gas poolsThis essay deals in detail with the inhomogeneity of the crust structure and the variation of the Moho, the process of deep dynamics and also relations of deep dynamic process to the formation of oil-gas pools in Songliao Basin.

Formation mechanism of the graphite-rich protective layer in blast furnace hearths

A long campaign life of blast furnaces is heavily linked to the existence of a protective layer in their hearths. In this work, we conducted dissection studies and investigated damage in blast furnace hearths to estimate the formation mechanism of the protective layer. The results illustrate that a significant amount of graphite phase was trapped within the hearth protective layer. Furthermore, on the basis of the thermodynamic and kinetic calculations of the graphite precipitation process, a precipitation potential index related to the formation of the graphite-rich protective layer was proposed to characterize the formation ability of this layer. We determined that, under normal operating conditions, the precipitation of graphite phase ~om hot metal was thermodynamically possible. Among elements that exist in hot metal, C, Si, and P favor graphite precipitation, whereas Mn and Cr inhibit this process. Moreover, at the same hot-face temperature, an increase of carbon concentration in hot metal can shorten the precipitation time. Finally, the results suggest that measures such as reducing the hot-face tem- perature and increasing the degree of carbon saturation in hot metal are critically important to improve the precipitation potential index.

Investigation of the Corrosion and Passive Behavior of HP-13Cr Stainless Steel in Formate Annulus Protection Fluid

The corrosion and passive behavior of HP-13Cr stainless steel(HP-13Cr SS)in formate annulus protection fluid was investigated.HP-13Cr SS exhibited good passive behavior in clean formate annulus protection fluid,which was attributed to a thinner and more dense passive film mainly composed of Cr_(2)O_(3).In the formation water solution,the passive film was composed of metastable Cr(OH)3,which was explained by the isoelectric point theory,resulting in the deterioration of the passive behavior of HP-13Cr SS.When the formation water penetrated the formate annulus protection fluid,a large number of loose FeCO_(3)particles formed in the corrosion scales,thus HP-13Cr SS suffered severe corrosion.Therefore,avoiding formation water penetrating the formate annulus protection fluid is conducive to improving the service life of HP-13Cr SS oil tubes in extremely aggressive environment.

Large-scale Tazhong Ordovician Reef-flat Oil-Gas Field in the Tarim Basin of China

The Tazhong reef-fiat oil-gas field is the first large-scale Ordovician organic reef type oil-gas field found in China. Its organic reefs were developed in the early Late Ordovician Lianglitag Formation, and are the first large reefs of the coral-stromatoporoid hermatypic community found in China. The organic reefs and platform-margin grain banks constitute a reef-flat complex, mainly consisting of biolithites and grainstones. The biolithites can be classified into the framestone, baffiestone, bindstone etc. The main body of the complex lies around the wells from Tazhong-24 to Tazhong-82, trending northwest, with the thickness from 100 to 300 m, length about 220 km and width 5-10 km. It is a reef-flat lithologic hydrocarbon reservoir, with a very complex hydrocarbon distribution： being a gas condensate reservoir as a whole with local oil reservoirs. The hydrocarbon distribution is controlled by the reef complex, generally located in the upper 100-200 m part of the complex, and largely in a banded shape along the complex. On the profile, the reservoir shows a stratified feature, with an altitude difference of almost 2200 m from southeast to northwest. The petroleum accumulation is controlled by karst reservoir beds and the northeast strike-slip fault belt. The total geologic reserves had reached 297.667 Mt by 2007.

Mechanism of Silurian Hydrocarbon Pool Formation in the Tarim Basin

There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong （central Tarim） and Tabei （northern Tarim） areas are the results of destruction of hydrocarbon pools formed in the first-stage, and the asphaltic sandstones around the Awati Sag were formed in the second-stage. The hydrocarbon migration characteristics reflected by the residual dry asphalts could represent the migration characteristics of hydrocarbons in the Silurian paleo-pools, while the present movable oil in the Silurian reservoirs is related to the iater-stage （the third-stage） hydrocarbon accumulation.

Potential Calculation on the Oil-Gas Pipeline with Geosynthetic Clay Liners Based on BEM

Put geosynthetic clay liners around underground oil-gas pipelines can reduce the potential damage to environment but it will also affect the distribution of cathodic protection current. Geosynthetic clay liners can be regarded as anisotropic soil structure and the potential distribution on the pipeline between two adjacent cathodic protection stations was calculated based on boundary element method (BEM). The calculation results indicate that potential distribution on the pipeline with geosynthetic clay liner is lower than before. A 1500 m built pipeline with geosynthetic clay liners was selected to be calculated and to perform field test, which shows that the calculation results tally well with the field test results and the validity of the arithmetic in this paper was verified.

库车山前气体钻井技术应用效果评价

塔里木油田从2006年来在库车山前大北、博孜、迪北3个区块开展了气体钻井技术的探索与应用,取得了显著效果。其中,针对塔里木库车山前高陡巨厚砾岩层研磨性强、可钻相差、井壁稳定性差等,开展了空气钻井技术的探索、升级配套以及优化完善,有效解决了库车山前砾石核心区地层难钻的问题,大幅提高了钻井效率,新实施井平均机械钻速达到6.93 m/h,是同区钻井液钻进的两倍以上,钻井周期较设计缩短54.2%;针对迪北构造阿合组致密敏感性储层采用氮气钻完井技术,“零污染”钻进,扩大了勘探发现,提高了开发产能,DB104井日产气量高达72.6×104m3,日产油量51.36 m3,与同区块常规钻完井方式相比,大幅度提高了日产气量。但气体钻完井中仍然存在油钻杆完井管柱不能满足长效安全生产等问题,建议持续开展技术攻关,以保障氮气钻安全钻进和开发。通过文章的梳理,有助于塔里木油田气体钻井技术进一步发展,同时为国内其他区块的气体钻井技术升级提供借鉴。

工业广场保护煤柱开采井筒破损致因及防治技术

针对工业广场保护煤柱开采导致井筒破损的问题,以大社煤矿为工程背景,分析工广煤柱开采井筒围岩移动变形特征,揭示井筒破损致因;提出工广内后续工作面开采防治井筒破坏方案,形成相应的施工技术,并成功应用工程实践。研究表明:该矿工广内92606工作面邻近副井,开采引发的井筒竖向附加力是井筒破坏的致因;如不提前采取防治措施,后续92606外工作面开采,将导致副井井筒发生二次破坏;研究提出的不停产单卸压槽防治方案,具有不影响矿井生产、卸压率高、施工简单、成本低等优点。采用壁后注浆、开切卸压槽、架设密集井圈等技术,顺利完成了该矿不停产防治副井井筒破损工程。监测表明,该井筒竖向和环向应力,均小于井壁极限.承载力,处于安全状态,运行良好,达到了预期效果。

页岩储层钻井液-压裂液复合损害机理及保护对策

为了分析钻井液与压裂液复合作用导致的储层损害,考虑油基钻井液侵蚀页岩矿物诱发的裂缝延伸,建立钻井液动态侵入深度预测方法,评价页岩裂缝面力学性质弱化、裂缝闭合与岩粉堵塞导致的天然/水力裂缝损害,提出钻井液-压裂液复合作用储层损害模式,揭示页岩油气层钻完井损害机理并提出保护对策。研究表明,钻开储层过程中,钻井液通过页岩诱导裂缝和天然裂缝深度侵入储层,侵蚀页岩矿物并导致侵入带页岩力学性质普遍弱化;水力压裂过程中,钻井液-压裂液复合作用进一步弱化页岩力学性质,导致生产过程裂缝更易闭合并发生岩粉脱落,诱发天然/水力裂缝应力敏感损害和固相堵塞损害,造成钻井液-压裂液复合作用带裂缝导流能力大幅降低,制约页岩油气井高产稳产。提出了防塌防漏加速储层段钻进、化学成膜防止页岩裂缝面力学性质弱化、强化页岩裂缝封堵减少钻井液侵入范围、优化压裂液体系保护裂缝导流能力的页岩储层保护对策。

鄂尔多斯盆地北部直罗组古河道砂体分布区矿井涌水模式

近十几年来,鄂尔多斯盆地北部煤矿开采频频受到了直罗组地下水的威胁,甚至出现了突水事故。区内以直罗组地下水为充水水源的大水矿井连片分布,且与直罗组古河道砂体关系密切。为阐释神府南区直罗组古河道砂体分布区矿井涌水模式,在直罗组古河道砂体空间分布及其对地下水赋存控制作用研究的基础上,从研究区尺度、井田尺度和工作面尺度,分析了直罗组古河道砂体与矿井涌水的关系,提出了直罗组古河道砂体下矿井涌水模式。结果表明:神府南区直罗组古河道冲刷带沿红碱淖—尔林兔—锦界一线发育,冲刷带内延安组第5段几乎被冲刷剥蚀殆尽,在局部地区延安组第4段也遭受了冲刷。根据砂分散体系分析和隔水岩组发育特征,将冲刷带内充填沉积的古河道砂体分为3级。直罗组古河道砂体富水性的强弱主要受控于砂体规模、物性特征和风化作用,一级砂体(主河道)区域富水性强于二级砂体(分支河道)及三级砂体(三角洲间湾、分流间湾)区域,当砂体遭受风化后,其富水性将进一步增强。基于不同尺度下砂体分级、风化砂体厚度与矿井涌水关系的分析,提出了研究区东部现阶段古河道砂体下生产矿井的3种涌水模式。强涌水模式,主要位于一级砂体分布区,风化砂体厚度一般≥30 m。中等涌水模式,主要位于一级砂体的边缘或二级砂体区域,风化砂体厚度一般10~30 m。弱涌水模式,主要位于三级砂体区域,风化砂体厚度一般<10 m。

耕地“进出平衡”政策执行的偏移风险、形成路径与规避体系研究

研究目的:以“内涵阐释—风险辨识—路径分析—规避体系”为逻辑主线,客观认识耕地“进出平衡”政策执行的偏移风险类型、风险来源与形成路径,探究耕地“进出平衡”政策执行偏移风险新命题,以期为提高新时期耕地用途管制政策的稳定性与连续性提供理论参考。研究方法:理论分析法和归纳演绎法。研究结果:(1)耕地“进出平衡”政策执行的偏移风险主要包括组织矛盾、保障滞后、利益冲突和监管缺失;(2)规划冲突与权责模糊、资金技术的双重约束、多元主体利益冲突以及对非耕行为的负激励程度不足是造成政策执行偏移的主要风险源;(3)“制度环境—利益互异—执行偏移”的逻辑主线,可解释耕地“进出平衡”政策偏移风险的形成路径;(4)规避耕地“进出平衡”政策执行偏移风险,需借助规划管理、资金技术、利益分配和科技预警等手段。研究结论:耕地“进出平衡”政策的执行,应重视政策演化不同阶段不同偏移风险的差异性,构建相应的风险规避体系。

北京西山门头沟地区主要地质遗迹分布特征及形成演化

北京门头沟区处于燕山与太行山的交汇处,山地面积占98.5%,属北京西山的核心地区,在漫长的地质历史长河中,留下了丰富的地质遗迹。针对该区地质遗迹分布特征、形成演化缺乏系统研究,并制约其保护利用等问题,在充分利用前人成果的基础上,通过遥感解译、地面调查、岩矿鉴定等,对该区地质遗迹类型进行系统梳理,深入探讨了区内地质遗迹分布特征和形成演化。结果表明:(1)该区地质遗迹丰富、类型多样;目前已查明的各类地质遗迹有100处,涵盖地质剖面、地质构造、古生物化石、地貌景观等多个类型。(2)青白口系、马兰黄土等地质剖面及古生物化石类地质遗迹的分布与中新元古界—第四系地层出露区密切相关;褶皱、断裂等主要分布在妙峰山镇—斋堂镇的中高山地区;燕山期酸性岩体地质遗迹主要沿大型断裂分布;黄土台地、河流阶地、峡谷以及水体景观类主要沿永定河干流及大型支流分布。(3)区内发生多次海侵,形成了诸多地层地质剖面遗迹,芹峪运动、蓟县运动、燕山运动等留下了多处不整合面、断层、褶皱等构造形迹,也主导了多期多种矿床形成。研究结果可为区内地质遗迹资源深入研究及其保护利用提供重要依据。

珠江三角洲沙田的景观特征与生物文化多样性解析

分析自然和文化协同驱动下珠江三角洲沙田景观特征与生物文化多样性的演变机制,为沙田文化景观的保护和可持续发展提供理论参考。以生物文化多样性理论为支撑,通过划分沙田景观类型并选取连续样方对沙田典型单元的景观特征及其生物文化多样性的关联进行剖析;对研究单元的“城-水-田”肌理及模式进行概括和纵向对比,量化分析城市化影响下三角洲典型沙田景观特征的演变机制。人工干预对沙田景观特征和生物文化多样性的影响主要表现在人为垦殖、沙田农业生计活动、多样化的文化群体的生活实践等方面。珠江三角洲的农业地区城市化和农村人口向城市中心迁移已成为改变沙田生物文化多样性的主要驱动因素,不同程度的城镇化影响了沙田“城-水-田”的空间肌理及景观构成模式。

破碎地层护壁防塌剂研制及性能评价

针对顺北奥陶系碳酸盐岩地层揭开后坍塌掉块严重,遇阻卡钻频发的难题,以二甲基二烯丙基氯化铵、N,N-二甲基丙烯酰胺及自制含甲氧基硅烷基团的有机硅单体为原料,合成了可与碳酸盐岩地层发生键合反应的抗高温有机硅护壁防塌剂SMHB-1。通过红外光谱、核磁共振氢谱及热重等表征了产物的分子结构及稳定性,并评价了其搭接抗剪切强度、降滤失性能及封堵性能等进行了研究。结果表明,1.5%SMHB-1溶液处理过的碳酸盐岩岩心片的搭接抗剪强度可达到0.2 MPa, 160℃老化16 h后1%SMHB-1可使4%土浆滤失量降低60.7%,SMHB-1可降低体系渗透率降约61.68%,并且与现场钻井液的配伍性能好。以SMHB-1为核心的水基护壁防塌钻井液体系在顺北X井奥陶系地层进行应用,奥陶系井壁稳定性好,没有掉块产生,扭矩平稳,起下钻顺利,无阻卡,试验井段平均井径扩大率8.6%~11.4%。

顺北油气田特深井钻井关键技术现状与发展建议

顺北油气田资源储量丰富,但油气埋藏深,储层具有超深、高压、超高温特点,被公认为钻完井的“世界禁区”。因此,探索适用于顺北油气田特深井的高效钻井技术系列,对加快该油气田高效开发具有重要意义。针对顺北油气田钻井技术难点,通过多年技术攻关和实践,形成了高效钻井技术系列,主要包括井身结构优化设计技术、古生界分层提速技术、复杂地层井筒强化技术、易漏地层高效防漏固井技术、高温储层高效定向技术和断控型储层保护技术。通过强化地质工程一体化并推广应用成熟技术,在井深逐年增加的情况下,钻井周期逐年缩短,保障了顺北油气田高效勘探、效益开发。指出需持续提升一井多控,断裂间安全钻井、异常高压工程应对能力,加强工具、材料耐温性能等关键核心技术攻关力度,提出应加大万米深井钻探的基础理论、关键技术与装备攻关研究,以进一步推动顺北油气田勘探开发步伐,保障安全成井,不断解锁“中国深度”。

自张式膨胀管技术的研究与应用

孔内膨胀管钻探技术是保障复杂地层孔壁稳定的有效技术之一。本文针对易出现缩径、坍塌、掉块的强水敏性地层,提出了一种自张式膨胀管护壁方法,并根据该方法的护壁原理研制了相适配的新型扩孔钻具、膨胀管及膨胀管投送装置,在不改变钻孔结构的情况下,对复杂孔段进行局部扩孔,投送膨胀管借助自身张力自然弹开而固定在相应的扩孔段,实现钻进时护壁。通过室内及现场试验对机具进行了优化,最终取得了良好的应用效果。试验证明:该方法操作简单可靠、易于定位,相较于水泥浆护壁具有处理速度快、停待时间短、减少重复处理等优势,适用于岩心钻探领域多孔段复杂地层的固壁与护壁,有利于降低孔内事故处理的成本、提高钻进效率,具有较好的推广应用价值。

环保型弱凝胶护壁护心钻井液研究与应用

海域浅层气地质调查和盐湖环境科学钻探在松散砂岩钻探取样工程中,存在孔壁易坍塌、成孔率低等技术难题,为此开展了松散砂岩地层环保型弱凝胶护壁护心钻井液技术研究。通过弱凝胶结构研究及成胶剂、交联剂及抗盐降滤失剂等材料优选,研发了一套环保型弱凝胶护壁护心钻井液,评价了钻井液的流变性、滤失性、抑制性、护心性能、环保性能等性能,并在山西某盐湖环境科学钻探工程进行现场应用。室内测试及现场应用结果表明:研制的弱凝胶护壁护心钻井液具有良好的流变性、降滤失性、抑制性(岩屑回收率96.3%)、护壁护心性能及环保性能(BOD5/COD比值24.6%,EC50值47950 mg/L),能有效解决松散砂岩类地层孔壁坍塌、岩屑不易携带等问题,在松散地层钻探工程中具有广阔的应用前景。

正向压力封堵钻井液技术与测试

正压封堵钻井液技术是近些年来研究较多和发展较快的一种井壁强化技术。正向压力钻井液技术,就是通过加入膜化剂,使钻井液在泥岩等地层井壁表面形成一层较高质量的隔离膜,封堵地层裂缝,阻止钻井液滤液进入地层,从而实现提高地层承压封堵能力,起到有效保护储层和维持井壁稳定的目的,为钻完井期间达到井下安全提供技术保障。本文通过调研常用的正向压力技术,从结构研究和优选实验,形成正压封堵剂XHY,形成了适合于某区块的正压封堵钻井液技术,并在大港埕海新区浅层及深部地层进行了现场应用。

我国钻井液技术难题、新进展及发展建议

系统地梳理了超深/特深层、非常规、深水、干热岩、极地、天然气水合物等复杂地层钻探过程中面临的钻井液技术难题,探讨了关键科学问题与核心工程难题,结合近年来的钻井液技术进展,介绍了钻井液技术最新进展。针对复杂地层钻井过程中遇到的高温高压高盐、泥页岩水化严重、井壁失稳、大温差、井漏、储层损害,以及钻井液维护自动化程度低等问题,国内外学者研发了抗高温高盐水基/油基钻井液、恒流变钻井液、抗超高温泡沫钻井液、环境友好型超低温钻井液、智能温压响应承压堵漏材料、可降解储层保护材料、钻井液在线监测与自动加料系统等关键材料、体系与装备。但随着地质、工程环境愈加复杂,钻井液材料仍面临抗超高温高盐、超长时间稳定、防塌固壁、恶性漏失以及钻井液性能自动化调控等重大技术瓶颈。为满足复杂地层钻探过程中钻井液性能需求,未来还需深入研究钻井液处理剂在极端条件下的起效/失效机理,钻井液处理剂在微观-介观-宏观等不同尺度下的构效关系变化及作用机制,建立安全高效的钻井液多功能一体化调控方法,构建智能钻井液理论与技术,为实现复杂地层安全高效经济环保钻井提供关键技术支撑。