利用地震属性研究准噶尔盆地西北缘拐19井区下侏罗统三工河组沉积环境

在准噶尔盆地西北缘，寻找岩性圈闭油气藏已是至关重要的问题。但人们几乎还是用常规的手段来寻找岩性油气藏，没有实质性进展。本文是以利用宽方位角采集的地震数据为基础，对数据进行高保真资料处理和参考标准层的层拉平解释。利用前人的区域地质研究成果和钻井解释成果对侏罗系的沉积环境进行了精细的描述，确定了拐19井区在下侏罗统三工河组的出油层段附近的沉积环境由湖泊相－三角洲前缘相－河流相－湖泊相的演化过程。利用地震属性解释的结果也能较好地反映目标区的沉积环境变迁，并且与区域地质、测井解释结果相吻合，为寻找油气提供了很好的依据。由此得出利用地震属性可以进行沉积环境变迁分析，为油田寻找岩性圈闭及油气藏做出贡献。     

Multi‐year water balance assessment of a newly constructed wetland,Fort McMurray,Alberta

Oil sands mining in Alberta transforms the boreal landscape of forests and wetlands into open pits, tailings ponds and overburden piles. Whereas reclamation efforts have primarily focused on upland forests, rebuilding wetland systems has recently become a motivation for research. Wetland creation and sustainability in this region is complicated by the sub‐humid climate and salinity of underlying mining material. In 2012, Syncrude Canada Ltd. completed the construction of the Sandhill Fen Watershed (SFW), a 52‐ha upland‐wetland system to evaluate wetland reclamation strategies on soft tailings. SFW includes an active pumping system, upland hummocks, a fen wetland and underdrains. To evaluate the influence of management practices on the hydrology of the system, this study reports the water balance from January 2013 to December 2014, the first 2 years after commissioning. A semi‐distributed approach was taken to examine the fluxes and stores of water in uplands and lowlands. Natural and artificial inputs and outputs were measured using a series of precipitation gauges and pumps, and evapotranspiration was quantified using three eddy covariance towers. A series of near surface wells recorded water table position. Both 2013 and 2014 were normal rainfall years, with 2013 having more and 2014 less snow than normal. In 2013, inflow/outflow from pumping was the predominant hydrological fluxes, resulting in considerable variability in water table position and storage changes throughout the summer. In 2014, the artificial addition of water was negligible, yet the water table remained near the surface in lowland locations, suggesting that wetland conditions could be maintained under current conditions. Evapotranspiration rates between uplands and lowlands were similar between years and sites, ranging from 2.2 ± 1.8 to 2.5 ± 1.2 mm/day and were largely controlled by climate. These rates were less than nearby older upland systems, suggesting that water balance partitioning will change as vegetation develops. Comparison between years and with natural systems provides insight on how management practices influence hydrologic dynamics and the overall water balance of the SFW. Copyright © 2016 John Wiley & Sons, Ltd.     

Large‐scale poroelastic fractured reservoirs modeling using the fast multipole displacement discontinuity method

An effective approach to modeling the geomechanical behavior of the network and its permeability variation is to use a poroelastic displacement discontinuity method (DDM). However, the approach becomes rather computationally intensive for an extensive system of cracks, particularly when considering coupled diffusion/deformation processes. This is because of additional unknowns and the need for time‐marching schemes for the numerical integration. The Fast Multipole Method (FMM) is a technique that can accelerate the solution of large fracture problems with linear complexity with the number of unknowns both in memory and CPU time. Previous works combining DDM and FMM for large‐scale problems have accounted only for elastic rocks, neglecting the fluid leak‐off from the fractures into the matrix and its influence on pore pressure and stress field. In this work we develop an efficient geomechanical model for large‐scale natural fracture networks in poroelastic reservoirs with fracture flow in response to injection and production operations. Accuracy and computational performance of the proposed method with those of conventional poroelastic DDM are compared through several case studies involving up to several tens of thousands of boundary elements. The results show the effectiveness of the FMM approach to successfully evaluate field‐scale problems for the design of exploitation strategies in unconventional geothermal and petroleum reservoirs. An example considering faults reveals the impact of reservoir compartmentalization because of sealing faults for both geomechanical and flow variables under elastic and poroelastic rocks. Copyright © 2015 John Wiley & Sons, Ltd.     

准噶尔盆地东部沙帐地区中二叠统平地泉组一段致密油源储组合模式

综合利用录井、镜下薄片及压汞等资料,对准噶尔盆地东部沙帐地区中二叠统平地泉组一段致密油储集层岩性、储集空间和孔隙结构等特征进行了分析,在此基础上结合平一段致密油纵向岩性组合特征及源储关系,总结了平一段致密油源储组合模式。研究发现平一段致密油储集层岩性以碎屑岩为主,云质类岩石次之,储层孔隙结构具"粗态型"、"偏细态型"和"细态型",储集空间表现为常规孔隙与纳米孔隙并存;平一段源储组合表现为"泥包砂"、"砂包泥"和"砂泥互层"。研究表明:平一段储集层表现为致密储层特征,纳米孔喉是致密油储层的主体孔喉,平一段致密油具有源储一体型、源储交接型和源储隔离型三类组合模式。     

准噶尔盆地油气源、油气分布与油气系统

准噶尔盆地是中国西部典型的多旋回叠合盆地,发育有石炭系、二叠系、三叠系、侏罗系、白垩系和古近系6套烃源岩,同时存在6大类原油和3大类天然气,广泛分布于盆地不同地区。西北缘原油总体相似,碳同位素组成轻(δ~(13)C-29‰),胡萝卜烷、类异戊二烯烷烃、三环萜烷、伽马蜡烷丰富,甾烷以C_(28)、C_(29)为主,基本没有重排甾烷,为第二类原油,来源于二叠系湖相烃源岩。腹部绝大多数原油与西北缘原油相似,但胡萝卜烷、类异戊二烯烷烃、伽马蜡烷等有差异,来源于不同凹陷的二叠系湖相烃源岩;少量原油碳同位素组成重(δ~(13)C-28‰~-26‰),Pr/Ph大于2.5,三环萜烷以C_(19)、C_(20)为主,藿烷丰富而伽马蜡烷极低,以C_(29)规则甾烷及重排甾烷为主,为第四类原油,来源于侏罗系煤系烃源岩。东部存在5种类型原油,第一类原油碳同位素组成特别重(δ~(13)C-26‰),来源于石炭系烃源岩;第二类原油与腹部地区绝大多数原油十分相似,来源于二叠系湖相烃源岩;第三类原油碳同位索组成轻,重排甾烷、Ts、C_(29)Ts及C_(30)重排藿烷异常丰富,来源于中上三叠统湖相烃源岩;第四类原油源于侏罗系煤系烃源岩;混合类原油为二叠系、三叠系、侏罗系原油的混合,各自贡献平均分别为20%、15%和65%。南缘存在4类典型原油,为第二、第四、第五和第六类原油,其中第二、第四类分别源于二叠系和侏罗系;第五类原油碳同位素组成轻(δ~(13)C-29‰)、Pr/Ph1.0、伽马蜡烷丰富且有两个异构体、Ts、C_(29)Ts、C_(30)重排藿烷、C_(27)~C_(29)异胆甾烷及C_(30)甲基甾烷丰富,来源于白垩系湖相烃源岩;第六类原油主要为中低成熟原油,碳同位素组成δ~(13)C~28‰~-26‰,C_(27)、C_(28)、C_(29)甾烷呈"V"型分布,甲藻甾烷异常丰富,来源于古近系湖相烃源岩。准噶尔盆地天然气有油型气、混合气和煤型气,前两类主要来源于二叠系湖相烃源岩和石炭系海相烃源岩,煤型气主要来源于石炭系和侏罗系煤系烃源岩。不同类型油气分布与不同时代烃源灶具有良好对应关系:石炭系油气主要分布于陆东-五彩湾;二叠系油气主要分布于西北缘、腹部与东部;三叠系原油仅分布于东部;侏罗系原油主要分布于东部与南部;白垩系原油仅分布于南缘中部;古近系原油仅分布于南缘西部。按照盆地构造特征及不同时代烃源灶与油气关系,将准噶尔盆地划分为西部、中部、东部、南部及乌伦古5个油气系统及15个子油气系统。     

Characteristics and Origin of Tight Oil Accumulations in the Upper Triassic Yanchang Formation of the Ordos Basin, North-Central China

The Upper Triassic oil accumulations in the Ordos Basin is the most successful tight oil play in China,with average porosity values of less than 10% and permeability values below 1.0 mD.This study investigated the geological characteristics and origin of the tight oil accumulations in the Chang 6 member of the Upper Triassic Yanchang Formation in the Shanbei area based on over 50,000 petrological,source-rock analysis,well logging and production data.The tight oil accumulation of the Chang 6 member is distributed continuously in the basin slope and the centre of the basin.The oilwater relationships are complex.Laumontite dissolution pores are the most important storage spaces,constituting 30%-60% of total porosity and showing a strong positive relationship with oil production.The pore-throat diameter is less than 1 μm,and the calculated critical height of the oil column is much larger than the tight sand thickness,suggesting that the buoyancy was probably of limited importance for oil migration.The pressure difference between the source rocks and sandstone reservoirs is inferred to have provided driving force for hydrocarbon migration.Two factors of source-reservoir configuration and laumontite dissolution contributed to the formation of the Chang 6 tight oil accumulations.Intense hydrocarbon generation and continuous sand bodies close to the hydrocarbon kitchen are the foundation for the large-scale oil distribution.Dissolution of feldspar-laumontite during the process of organic matter evolution generated abundant secondary pores and improved the reservoir quality.     

A Review of the Bentong-Raub Suture vis-à-vis New Insight of the Tectonic Evolution of Malay Peninsula, South East Asia

As a milestone of the entire energy industry, unconventional resources have inevitably swept the world in the last decade, and will certainly dominate the global oil and gas industry in the near future. Eventually, the “unconventional” will become “conventional”. Along with the rapid development, however, some issues have emerged, which are closely related to the viability of unconventional resources development. Under the current circumstances of low crude oil and gas price, coupled with the prominent environmental concerns, the arguments about the development and production of unconventional resources have been recently heated up. This work introduced the full-blown aspects of unconventional resources especially shale reservoirs, by discussing their concepts and definitions, reviewing the shale gas and shale oil development history and necessity, analyzing the shale plays’ geology and petroleum systems with respects to key hydrocarbon accumulation elements and mechanisms, and summarizing the technology resolution. This study also discussed the relevant key issues, including significant estimation uncertainty of technically recoverable resources, the equivocal understanding of complex geology preventing the production and technologies implementation optimization, the difficulties of experiences and technologies global expanding, and the corresponding risks and uncertainties. In addition, based on the latest production and exploration data, the future perspective of the unconventional resources was depicted from global unconventional resources assessments, technology development, and limitations constraining the development.     

伊通盆地鹿乡断陷C区块含油饱和度与含油性分析

综合研究伊通盆地鹿乡断陷双二段储层的岩性、含油性和含油饱和度,确定了适用于本区的含油饱和度计算方法,并与实际含油性进行了对比,分析了沉积和构造对含油性的影响。研究区双二段含油储层的岩性以粉砂岩、细砂岩和砂砾岩为主,含油级别为荧光级以上。根据阿尔奇公式计算出的含油饱和度大部分与实际的含油性相符合,并将含油饱和度70%、50%和38%值作为本区气层、油层、油水层和水层的区分标准。本区储层的含油性受到沉积和构造两方面的控制,沉积作用主要控制储层的岩石结构和物性,构造控制油气的聚集,即在构造高部位,实际含油饱和度比计算结果要高,而在构造低部位,实际含油饱和度比计算结果要低。     

油气上窜速度实用计算方法

油气上窜速度对钻井施工中下一步施工方案的制定具有重要参考价值。文章在总结分析前人经验的基础上结合现场施工实际对传统油气上窜速度计算公式加以修正,并对修正后的公式中涉及到的参数进行了逐一分析,在不影响正常施工工序的条件下使公式中各参数取值准确性进一步提高。通过现场工程测试,该方法简单实用且计算准确性较高。该计算方法在保证计算结果准确性的同时,也具备较强的现场可操作性,通过大量的实践检验后可进一步推广。     

Oil dispersal modelling: reanalysis of the Rena oil spill using open-source modelling tools

ABSTRACT

Oil spill forecast modelling is typically used immediately after a spill to predict oil dispersal and promote mobilisation of more effective response operations. The aim of this work was to map oil dispersal after the grounding of the MV Rena on Astrolabe Reef and to verify the results against observations. Model predictions were broadly consistent with observed distribution of oil contamination. However, some hot spots of oil accumulation, likely due to surf-zone and rip current circulation, were not well represented. Additionally, the model was run with 81 differing wind conditions to show that the events occurring during the grounding represented the typical likely behaviour of an oil spill on Astrolabe Reef. Oil dispersal was highly dependent on prevailing wind patterns; more accurate prediction would require better observations of local wind patterns. However, comparison of predictions with observations indicated that the GNOME model was an effective low-cost approach.