济阳坳陷沾化凹陷古近系沙河街组二段潜山周缘滩坝及物性特征

以高分辨率层序地层学理论为指导,通过岩心、录井和测井分析,对济阳坳陷沾化凹陷沙二段进行划分和对比。在识别和划分不同沉积相的基础上,结合古地理、古水深、物性和油气显示资料,着重对碎屑岩滩坝和生物滩沉积特征和储集层物性进行分析,结果表明:①生物滩和砂滩分布于平坦、开阔环境中,单层厚度薄,分布面积广;砂坝形成于有一定坡度和地形起伏的环境中,单层厚度大,分布局限。②古地貌和基准面旋回是断陷盆地潜山周缘滩坝储集层物性的主控因素。③潜山西侧生物滩物性最好,面积广、厚度薄,物性最有利;其次为东侧砂坝和砂滩,面积局限,厚度大,物性次之;北侧生物滩和砂滩物性较差,面积较广,厚度较大。     

Paleokarst system development in the San Andres Formation, Permian Basin, revealed by seismic characterization

Paleokarst systems are one of the major factors resulting in carbonate reservoir heterogeneity and compartmentalization. Nevertheless, few effective workflows have been proposed to map the 3D distribution of such systems. We describe a detailed seismic characterization approach integrating core, well log and rock physics analysis, to reveal a complex subsurface paleokarst system in the San Andres Formation, Permian basin, West Texas. In the area of high volume production, the collapsed paleokarst system is characterized by irregularly developed crackle and fracture breccias, mosaic breccias and cave fillings in the Upper San Andres Formation, which are delineated using seismic acoustic impedance. Along the transition from platform to basin, the paleokarst system is marked by a linear collapse including sags and small vertical faults that are recognizable in seismic imaging. Production data indicates that tight paleokarst zones cause reservoir compartmentalization and influence fluid communication between wells. The complex paleokarst system development is explained using a carbonate platform hydrological model, an outcrop analogue similar to modern marine hydrological environments within carbonate islands. Our method of model development for complex subsurface paleokarst systems may be applicable to other paleoenvironments.     

Analyzing Slug Tests in Wells Screened Across the Watertable: A Field Assessment

The slug test is the most widely used technique for the in situ estimation of hydraulic conductivityin confined and unconfined formations. Currently, there are no generally accepted methods in thegroundwater literature for the analysis of response data from slug tests performed in wells screenedacross the watertable. A field study was undertaken in an attempt to develop a set of practicalguidelines for tests conducted in such wells. Three wells, screened within unconsolidated materialexhibiting a range of hydraulic conductivities (.05–30.0 m/day), were installed to depths of up to9 m (30 ft) in Kansas River alluvium that ranges in thickness from 15 m to 21 m (50 ft to 70 ft)near Lawrence, Kansas. Intensive well-development efforts removed any drilling debris that couldinterfere with well-formation hydraulics. Once the wells were developed properly, a series of slugtests was performed at each well. The tests were designed to assess the role of the unsaturatedzone and the appropriateness of assuming a fixed hydraulic head upper boundary. The results ofthis investigation can be summarized as follows: (1) the sufficiency of well development shouldbe based on repeat slug tests and not the clarity of pumped water; (2) the effective screen radiusfor best model analysis should be based on a mass balance and not nominal screen dimensions;(3) the watertable can be represented as a constant head boundary and flow in the unsaturatedzone can be ignored in most situations; (4) conventional techniques for the analysis of slug-testdata seem to be reasonable for slug tests conducted in wells screened across the watertable, whenused with the appropriate effective screen radius and normalized head range; and (5) fluctuationsin the watertable elevation through time can be exploited to obtain some insight into the natureof vertical variation in hydraulic conductivity at a well. The results of this investigation indicatethat multiple slug tests should be performed at wells screened across the watertable in order toreliably assess the sufficiency of well development and the appropriateness of conventional theory.     

Quantitative mapping of active mud volcanism at the western Mediterranean Ridge-backstop contact

Based on a new quantitative analysis of sidescan sonar data combined with coring, we propose a revised model for the origin for Mediterranean Ridge mud volcanism. Image analysis techniques are used to produce a synthetic and objective map of recent mud flows covering a 640 × 700 km² area, which represents more than half of the entire Mediterranean Ridge mud belt. We identify 215 mud flows, extruded during the last 37,000–60,000 years. This time period corresponds to the limit of penetration of the sonar, that we evaluate through geoacoustic modeling of the backscattered signal returned by the mud breccia-hemipelagites contact, and calibrate by coring. We show that during this period, at least 96% of the mud volume has been extruded at the Mediterranean Ridge-Hellenic backstop contact, the remaining being scattered over the prism. We suggest that the source is a Messinian (5–6 Ma) mud reservoir that remained close to the backstop contact, at variance with the classical transport-through-the-wedge model. A revised mud budget indicates that steady-state input is not needed. We propose that the source layer was deposited in deep and narrow pre-Messinian basins, sealed by Messinian evaporites, and finally inverted in post-Messinian times. Onset of motion of the Anatolia-Aegea microplate in the Pliocene resulted in change from slow to fast convergence, triggering shear partitioning at the edges of the backstop and basin inversion. Mud volcanism initiation is probably coeval with the latest events of this kinematic re-organization, i.e. opening of the Corinth Gulf and activation of the Kephalonia fault around 1–2 Ma.     

川西拗陷须五段非常规气形成条件分析

随着对非常规气蔵的研究方法和开采手段的升级,使页岩气得以开发。川西拗陷须五段常规的思维是把它作为烃源岩来认识的,运用非常规页岩气的研究理念和方法,针对川西拗陷两条野外剖面(莲花剖面、万家坪剖面)及6口取心井(XYHF-1井,XYHF-2井,X503井,FG5井,GH2井,MY1井)的岩心观察、取样分析测试,以分析川西拗陷须五段具有形成非常规气蔵的条件,并用3种不同的表征方法(激光共聚焦法、高压压汞法、氮气吸附法)对须五段内不同类型的岩石进行孔隙度、渗透率及其连通性时行表征,结果表明:细砂岩中不同类型孔隙的孔隙度为0.41%～6.65%,平均总孔隙度为2.14%;泥(页)岩的孔隙度为1.51%～5.99%,总孔隙度为2.70%。微米CT扫描发现须五段上亚段细砂岩的连通性好于下亚段,中亚段以粉砂岩为主,孔隙连通性差,有机质含量低;泥(页)岩的孔隙连通性也差,孔隙发育依附于有机质的发育,泥(页)岩样品的有机碳含量主要分布在0.5%～3%之间。综合评价认为马井-邡、崇州-郫县、新场-丰谷等地区成蔵条件较好,为I类地区,是川西坳陷须五段页岩气的目标区域。     

滇西崇山剪切带南段左行走滑作用的构造特征及时代约束

作为保山地块与兰坪-思茅盆地的重要边界,崇山剪切带新生代以来经历了多阶段的构造变形;其中以大规模走滑韧性剪切作用最为明显,表现为北段以右行走滑剪切为主、南段以左行走滑剪切为主.本文通过对崇山剪切带南段永保桥-瓦窑桥剖面出露的崇山群石英片岩、片麻岩及糜棱岩等进行详细露头解析、室内显微构造观察以及变形石英的EBSD组构分析,认为崇山剪切带南段的岩石新生代以来至少经历了两期不同环境下的韧性变形:第一期(D1)为纯剪条件下的收缩变形,发生的温度条件大约在550 ～ 650℃(角闪岩相),表现为一些褶皱构造、石香肠或透镜体构造的发育及石英的C轴组构图呈斜方对称式;第二期(D2)为单剪递进条件下的左行走滑剪切变形,表现形式为走滑剪切面理的发育及各类岩石遭受韧性剪切变形从而改造成糜棱岩.此外,在崇山剪切带内发育一套含电气石花岗质脉体,根据详细的露头解析及显微构造分析,本文认为该套含电气石花岗质脉体是左行剪切作用初期阶段伴随的深熔作用的产物,为同剪切花岗岩脉.本文选取了两个含电气石花岗质脉体的样品进行了LA-ICP-MS锆石U-Pb测年,分别得到21.7±0.3Ma和22.7±0.3Ma的锆石U-Pb年龄,进一步表明了崇山剪切带南段的左行剪切作用起始时代在22Ma左右或略早于22Ma.     

低渗透储层成岩作用定量表征与成岩储集相——以吉林新立油田泉头组三、四段为例

作者采用铸体薄片、阴极发光、扫描电镜等手段,统计了新立油田泉头组三、四段储层的视压实率和视胶结率,对成岩作用强度进行了定量表征。引入了成岩系数和成岩储集相的概念,并按照成岩系数大小,将储层划分为4种成岩储集相,即强溶蚀次生孔隙成岩储集相(A相),中等压实-弱、中胶结混合孔隙成岩储集相(B相),强压实-弱、中胶结混合孔隙成岩储集相(C相)和碳酸盐强胶结成岩储集相(D相)。其中以A相最有利于油气聚集,B相次之,C相较差,D相最差。分析了各类成岩储集相特征和演化,认为晚成岩A亚期的酸性水溶蚀作用形成次生孔隙是改善储层物性的关键因素。     

Seismic inversion as a predictive tool for porosity and facies delineation in Paleocene fluvial/lacustrine reservoirs,Melut Basin,Sudan

The Melut Basin is a rift basin in the interior Sudan linked to the Mesozoic-Cenozoic Central and Western African Rift System. The Paleocene Yabus Formation is the main reservoir deposited in heterogeneous fluvial/lacustrine environment. Delineation of channel sandstone from shale is a challenge in reservoir exploration and development. We demonstrate a detailed 3D quantitative seismic interpretation approach that integrates petrophysical properties derived from well logs analysis. A porosity transform of acoustic impedance inversion provided a link between elastic and rock properties. Thus, we used seismic porosity to discriminate between different facies with appropriate validation by well logs. At the basin scale, the results revealed lateral and vertical facies heterogeneity in the Melut Basin. Good reservoir quality is observed in the Paleocene Yabus Formation. The sand facies indicated high porosity (20%) corresponding to low acoustic impedance (20000–24000 g ft/(cm3.s)). However, lower quality reservoir is observed in the Cretaceous Melut Formation. The porosity of sand/shale facies is low (5%), corresponding to high acoustic impedance (29000–34000 g ft/(cm3.s)). This suggests that the Yabus Sandstone is potentially forming a better reservoir quality than Melut Formation. At the reservoir scale, we evaluated the facies quality of Yabus Formation subsequences using petrophysical analysis. The subsequences YB1 to YB3, YB4 to YB7 and YB8 to YB10 showed relatively similar linear regressions, respectively. The subsequence of YB4 to YB7 is considered the best reservoir with higher porosity (25%). However, subsequence YB1 to YB3 showed lower reservoir quality with higher shale volume (30%). This attributed to floodplain shale deposits in this subsequence. Similarly, the high porosity (20%) recognized in deeper subsequences YB6 to YB9 is due to clean sand facies. We learnt a lesson that appropriate seismic preconditioning, exhaustive petrophysical analysis and well log validation are important keys for improved reservoir quality prediction results in fluvial/lacustrine basins.     

Sustainable development and management of an aquifer system in western Turkey

This study presents the establishment of sustainable development and management policies for the Küçük Menderes River Basin aquifer system in western Turkey. Geological, hydrogeological, and geophysical data are used conjunctively to define various hydrogeological units and their geometry. Distributions of hydraulic-parameter values and recharge are estimated by geostatistical methods and hydrologic simulations, respectively. A finite-difference groundwater flow model is used to represent the unconfined flow in the aquifer system. The model has been calibrated under steady state and transient conditions. The resulting model was used to test seven management scenarios for a planning period of 21 years to determine the so-called safe yield and sustainable yield of the aquifer system and to investigate the potential impacts of four planned surface water reservoirs on groundwater resources in the basin. The results demonstrate that the continuation of the present pumping rates exceeds both the safe yield and the sustainable yield of the aquifer system. Consequently, the growing need for irrigation water should be met by the construction of the planned surface water reservoirs and the implementation of efficient water management policies and plans.

---

Resumen Este estudio presenta el establecimiento de políticas sustentables de desarrollo y gestión en el sistema acuífero de la cuenca del río Küçük Menderes, al Oeste de Turquía, para lo que se ha utilizado datos geológicos, hidrogeológicos y geofísicos de forma conjunta de cara a definir diversas unidades hidrogeológicas y su geometría. La distribución de los parámetros hidráulicos y de la recarga ha sido estimada mediante métodos geoestadísticos y simulaciones hidrológicas, respectivamente. Se ha empleado un modelo de las aguas subterráneas en diferencias finitas para representar el flujo no confinado en el sistema acuífero, el cual se ha calibrado bajo condiciones estacionarias y transitorias. El modelo resultante ha sido usado para contrastar siete escenarios de gestión durante un período de planificación de 21 años con el fin de determinar el punto de explotación segura y sustentable del sistema acuífero, así como para investigar los impactos potenciales sobre los recursos subterráneos de los cuatro embalses superficiales que se hallan en proyecto. Los resultados demuestran que el mantenimiento de las tasas actuales de extracción del acuífero supera tanto el régimen de bombeo seguro como el sustentable del sistema. Por consiguiente, se debería compensar la necesidad creciente de agua para riego con la construcción de los reservorios superficiales previstos y con la implementación de políticas y planes de gestión eficiente del agua.

---

Résumé Cette étude présente la proposition dune politique de développement et de gestion durables du système aquifère du bassin du Petit Mendérès dans louest de la Turquie. Des données géologiques, hydrogéologiques et géophysiques ont été utilisées conjointement pour définir les différentes unités hydrogéologiques et leur géométrie. Les distributions des paramètres hydrauliques et de la recharge ont été estimées respectivement par des méthodes géostatistiques et des simulations hydrologiques. Un modèle découlement souterrain aux éléments finis a été utilisé pour représenter lécoulement non captif dans le système aquifère. Le modèle a été calibré dans des conditions de régimes permanent et transitoire. Le modèle résultant a servi à tester sept scénarios de gestion pour une période de programmation de 21 ans, afin de déterminer les débits de prélèvement sûr et durable dans le système aquifère et détudier les impacts potentiels de quatre réservoirs deau de surface en projet sur les eaux souterraines du bassin. Les résultats montrent que la poursuite des prélèvements au débit actuel excède aussi bien le débit dexploitation de sécurité que celui durable pour le système aquifère. Par conséquent, les besoins croissants deau pour lirrigation doivent être satisfaits par la construction des réservoirs projetés et par la mise en place de politiques et de plans de gestion de leau efficace.