松辽盆地梨树断陷苏家屯次洼页岩气成藏条件分析

通过对松辽盆地梨树断陷苏家屯次洼基本油气地质特征分析,认为营城组一段形成于断陷发育的鼎盛时期,发育稳定的大套泥岩夹薄砂岩地层.地化特征表明该段泥页岩具有有机质丰度较好、有机质类型丰富、热演化处于生气的成熟—高成熟阶段等特点.泥页岩中平均孔隙度达到3.52%,裂缝和微裂缝相对较发育,不仅可以为游离态气提供有利的储集空间,且脆性矿物含量相对较高,平均为41.1%,石英含量在15.1%~23.4%之间,岩石具有较好的可压性.钻井现场解析结果表明该段泥页岩中含气最高可达3.09 m3/t,且钻井气测全烃异常以及测试资料也表明该区页岩气的存在,说明该泥页岩中蕴藏着一定规模的页岩气资源,具有良好的资源前景和勘探潜力.      

泥页岩地层孔隙流体实验数据分析

由于缺乏取心资料和系统研究,使得国内外对于陆相盆地泥页岩含油率的测定还没有一个明确的标准,从而缺乏对泥页岩孔隙流体分布规律的认识。该文从实验室条件分析出发,采用常压干馏法和氦气法分别获取了泥页岩的含水量、含油量和孔隙度。实验结果表明,采用常规方法测量的泥页岩孔隙流体分布规律异于常规砂岩储层,集中表现在:(1)泥页岩地层的含水饱和度与含油饱和度之和大于100%;(2)随着孔隙度的增加,岩石单位含油体积变大,而单位含水体积不变。从测量方法和测量条件出发,剖析了出现该现象的原因,并给出了相应解释。该结果对于泥页岩非常规油气的深入研究和重新认识有一定的参考意义。      

基于复合材料桥塞的水平井套管分段压裂技术

介绍了基于复合材料桥塞的水平井套管完井分段压裂工艺管柱结构、工艺过程和关键技术。阐述了该工艺管柱中关键部件——复合材料桥塞和电缆坐封工具的结构、工作原理及性能特点。现场应用情况表明,复合材料桥塞可正常坐封丢手,射孔发射率100%,平均每个复合材料桥塞钻铣时间为30 min,达到国外标准;水平井套管分段压裂管柱结构合理,工艺优良,性能可靠,能够满足页岩气水平井射孔压裂联作的分段完井要求。建议进一步优化钻铣复合材料桥塞工艺和工具,扩充桥塞尺寸规格,使其形成系列化,以满足油田不同规格套管的需求。     

泥页岩裂缝性油藏非稳态产能影响因素

针对裂缝性泥页岩油藏开发的特殊性,基于质量守恒定律,在同时考虑裂缝及压力敏感性的情况下,建立了双孔单渗油藏中多分支垂直裂缝压裂井的数学模型,对其进行无量纲化后,采用隐式差分方法对无因次模型进行求解。根据油藏实际特点．建立地质模型。通过数值模拟计算研究了裂缝分支数、无因次裂缝半长、无因次窜流系数及无因次压敏系数等因素对不稳态产能的影响。研究结果表明．除人为可控的裂缝参数对产能的影响较大外,油藏自身的压敏系数也具有较显著的影响。为此,在该类油藏开发过程中,应在进行压裂方案优选以获取最大产能的同时,合理控制地层压降,以达到良好的开发效果．     

常规天然气分析标准对页岩气的适应性评价研究

由于页岩气与天然气成分上具有相似性,在页岩气勘探开发过程中一般采用常规天然气的分析方法及标准。对现有的管输天然气分析测试方法是否满足于页岩气现场测试要求进行了适应性研究,并在适应性研究的基础上提出页岩气分析测试方法标准制定的建议。     

An Offshore Benign WBM System Can Prevent Hard,Brittle Shale Instability

Abstract

In the Weizhou Southwest oilfields, drilling delays and suspension of wells prior to reaching the targets due to wellbore instability had occurred frequently. The hard, brittle shale played a problematic role. Conventional water-based drilling fluids did not conquer the problematic formation due to intrinsic performance deficiencies. Though oil-based drilling fluids are routinely preferred in more technically demanding applications, they are cause for increasing concern due to offshore environmental restrictions and expensive disposal costs. An environmentally acceptable water-based drilling fluid was developed to challenge the problematic formation based on the combination of methylglucoside-silicate concept. It stabilized the reactive shale by the same mechanism as oil-based drilling fluid in preventing shale hydration, pore pressure increase, and weakening of shale by effectively developing sufficient osmotic force to offset hydraulic and chemical forces acting to cause filtration flux into the hard, brittle shale. A field trial was initiated on the CNOOC 931 platform. The data from the pilot well showed that the novel drilling fluid exhibited excellent inhibition and lubricity that approached or even exceeded oil-based fluids.     

Effects of Ion Advection and Thermal Convection on Pore Pressure Changes in High Permeable Chemically Active Shale Formations

Wellbore instability problems are often encountered while drilling in water active shales due to changes in pore pressure. The change in pore pressure is caused by hydraulic, thermal, chemical, and electrical potential gradients. In all previous studies it has been found that the effects of ion advection and thermal convection have a negligible effect on changes in pore pressure for a range of very low permeable shale formations (>10^?5 md). This is an appropriate assumption for very low permeable shale formations. For high permeable shale formations (e.g., shale with a disseminated microfissure network), however, thermal convection and ion advection can play a significant role. The authors present a hydro-chemo-thermo-electrical model based on finite element method to investigate the effect of advection on ion transfer and thermal convection on temperature and their combined effect on pore pressure in shale formations. All equations are based on the thermodynamics of irreversible processes in a discontinuous system. The characteristic Galerkin discretization method is used to stabilize the solution of advection and convection equations in the finite element approach. Results of this study revealed that ion and heat transfer are controlled primarily by permeability of the shale formations. Movement of fluid into or out of the formation is due to a combination of hydraulic, chemical, electrical, and thermal osmotic flow. Results have also shown that in high permeable shale formations the chemical potential gradient between the pore fluid and drilling fluid reaches equilibrium faster than in low permeable shale formations. This is mainly due to the advection of ion from drilling fluid to the shale formation.     

Estimating Sand–Shale Formation Pore Pressure

Abstract

This article presents a comprehensive evaluation method of estimating sand–shale formation pore pressure by using sonic velocity and other logging data. The method takes the influence of porosity, density, shale content, effective stress, and some other physical properties of sand–shale formation on sonic velocity into account. The influence and related logging data are combined to estimate the effective stress, and then pore pressure can be obtained by the effective stress principle. Using this method, software was developed and it applied in the well site. Its applications indicate that this method can accurately estimate the abnormal pressure of a sand–shale formation.     

羧甲基羟丙基胍胶压裂液的研究与应用

苏北盆地致密砂岩段、有机质泥页岩段含油丰富,具有较大的开发潜力。该类油藏敏感性强,渗透率低,普通的胍胶体系容易对地层造成强水敏、强水锁伤害。针对此类储层特点,开展了羧甲基羟丙基胍胶压裂液配方研究,形成了适应不同温度的交联体系,具有水不溶物低,用量少,残渣低,易破胶;耐高温、高剪切,粘弹性好;返排率高,粘土抑制性能强等优点。经现场应用,可满足江苏油田非常规储层的压裂需要。     

河南油田页岩油长水平段水平井钻井实践

河南油田泌阳凹陷泥页岩油气藏储量丰富,是下一步河南油田的替代资源。水平井钻井技术是当前页岩油气开发的主流技术,应用水平井钻井技术,结合水力压裂技术能够实现致密页岩油气藏的商业开发。以泌页HF1井为例,从井身结构与井眼剖面设计、轨迹控制技术、钻井液技术和固井技术等方面介绍了河南油田页岩油长水平段水平井钻井施工中的关键技术,为类似区块应用水平井技术开发致密页岩油气藏提供技术借鉴。