Modeling deepwater seabed steady-state thermal fields around buried pipeline including trenching and backfill effects

Deepwater pipelines are designed to transport mixtures of oil and gas, and their associated impurities at wellhead temperatures that can be in excess of 149 °C (∼300 °F or 422 K) while the external temperature maybe in the range of 5 °C (∼41 °F or 278 K). Depending on the circumstances these pipelines may be buried for physical protection or for additional thermal insulation using robotic trenching equipment. This results in a complex cut and backfill geometry in the seafloor in addition to altering the thermal properties of the backfill. A two-dimensional boundary element model was developed specifically to address to investigate the local steady-state thermal field in the near field of the pipeline. The model allows one to account for the complex geometries in the near field associated with this burial technique, site-specific multi-layered soil conditions and the seawater adjacent to the seafloor. A parametric study was preformed to evaluate effects of the thermal power loss, burial depth, pipe diameter and soil thermal conductivity on the thermal field in the near field of a buried pipeline. The numerical examples illustrate the influence of the backfill thermal property on the temperature at the pipe wall, that the pipe diameter controls the required output thermal power needed to maintain the desired pipe wall temperature, and the importance of pipeline burial depth on seabed temperature distribution above the pipeline.     

GEOPHYSICAL EXPLORATION

正20141074Bao Xijie(Research Institute of Exploration and Development,Daqing Oilfield Company,PetroChina,Daqing 163712,China)Gather Optimal Processing and Application Effect of Prestack AVA Instantaneous Inversion     

HYDROGEOLOGY & ENGINEERING GEOLOGY

正1.HYDROGEOLOGY20142452Chang Chengcao(Institute of Coalfield Geological Survey and Design of Jilin Province,Changchun 130062,China)Hydrogeological Type Division of Coal Mine No.2Mine in Yitong Manchu Autonomous County,Jilin Province(Jilin Geology,ISSN1001-2427,CN22-1099/P,32(4),2013,p.129-131,3refs.)     

Introducing a new conceptual instantaneous unit hydrograph model based on a hydraulic approach

ABSTRACT

A novel approach is introduced for simulation of instantaneous unit hydrographs (IUHs). The model consists of a series of linear reservoirs that are connected to each other, and is referred to as the inter-connected linear reservoir model (ICLRM). By assuming the flow between two reservoirs is a linear function of the difference between the water levels in the reservoirs, a system of first-order linear differential equations is obtained as the ICLRM governing equation. By solving the equations, the discharge from the last reservoir is considered as an IUH. A small-scale laboratory device was constructed for the simulation of IUHs using the model. By studying four hydrographs extracted from the literature, and simulating them using both the ICLRM and the Nash model, it is concluded that the ICLRM can predict these hydrographs more accurately than the Nash model. Due to the simplicity of the construction and operation of the ICLRM and, more importantly, its visual aspect, the ICLRM may be considered as an effective educational tool for studying IUHs.     

南美Oriente盆地北部海绿石砂岩油藏特征及成藏规律

南美厄瓜多尔Oriente盆地斜坡带发育的白垩系Napo组高伽马特征的UT海绿石砂岩段是成熟探区新发现的隐蔽含油层段。本文分析了海绿石砂岩储层的矿物组成、孔隙结构、成岩作用、物性特点,并结合烃源岩评价与石油空间分布探讨海绿石砂岩油藏的成藏特征。海绿石粘土矿物以颗粒形式存在,与石英共同构成海绿石砂岩的颗粒组分,海绿石砂岩的孔隙结构具有双峰特征,束缚水含量高,属于中-低孔、中-低渗储层类型,孔隙类型主要是剩余粒间孔。海绿石砂岩储层中石英次生加大属Ⅱ级,长石碎屑颗粒发生溶蚀作用,含铁碳酸盐类胶结物发育,结合泥岩低的I/S混层比和高的最高峰温值T_max,指示海绿石砂岩层段属于中成岩阶段A期的产物。与海绿石砂岩油藏紧邻的大面积分布的Ⅱ₁腐泥型成熟烃源岩就是缓翼斜坡带的生烃中心,大面积连续发育的海绿石砂岩与之构成优越的源储组合,有利于上生下储式成藏。海绿石砂岩油藏表现为近源性、成藏晚期性等特点,规模发育的海绿石砂岩储层得以成藏的主要运聚机制是体积流和扩散流运聚机制。这对盆地其它油区同类油藏的发现具有重要的借鉴意义。     

四川盆地海相碳酸盐岩的油气成藏条件

四川盆地位于亚洲大陆中南部,是我国最大的外流盆地。油气资源评价结果(2008)表明,四川盆地海相地层待发现资源量约为50111.84×108m~3,资源勘探潜力巨大。本文从地层的划分、层序格架及层序岩相古地理特征等方面,对四川盆地海相碳酸盐岩油气成藏条件做了进一步研究。认为研究区烃源岩包括下志留统、中二叠统、上二叠统龙潭组和上三叠统须家河组等4套岩石,及局部发育的上二叠统大隆组。储集层粉为构造成因类和沉积成因类,构造成因主要包括裂缝性储层;沉积成因类储层主要是礁滩储层、内幕白云岩储层和风化壳岩溶储层。中二叠统气藏主要为自生自储的裂缝性气藏和台内滩相气藏;茅口组顶部和雷口坡组顶部发育风化壳型气藏;吴家坪组、长兴组及飞仙关组地层含礁滩型气藏;嘉陵江组和雷口坡组地层含内幕白云岩型气藏。     

斜列构造型式空间定位研究及其对隐伏矿脉预测的意义

斜列状的断裂、裂隙的排列组合,其中往往充填岩脉或矿脉,被称之为雁列或斜列构造。在内生脉状多金属矿床平面或剖面上,矿脉常出现斜列状排列的组合特征,关于它们的组合型式,特别是从空间上及定位分布规律方面,尚缺乏深入的研究。本文依据构成斜列型式的几个主要几何要素之间的关系将其划分为三种类型,进行了斜列构造型式空间定位分布特征的研究及其对隐伏矿脉预测意义的探讨。     

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。     

变形监测技术在库岸防治工程中的应用

针对库岸稳定性检测的需求,该文将现代变形监测技术应用于乌江彭水县水电站鹿角镇库岸防治工程,对地表进行抗滑桩顶和岸坡表层水平位移和垂直位移监测,地下进行岸坡深层水平位移监测。文章对边坡变形监测进行分析,主要包括岸坡表层变形情况、岸坡深层位移情况、重要建筑物基础不均匀沉降情况及抗滑桩顶变形初步分析。对库安防治工程进行预警分析,可保证彭水县水电站的安全。