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The Dongying Anticline, Bohai Bay Basin, Eastern China

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The Dongying Anticline, Bohai Bay Basin, Eastern China Open Geosci. 2016; 8:612–629 Research Article Open Access Fei Tian*, Jianting Yang, Ming Cheng, Yuhong Lei, Likuan Zhang, Xiaoxue Wang, and Xin Liu Geometry, kinematics and dynamic characteristics of a compound transfer zone: the Dongying anticline, Bohai Bay Basin, eastern China DOI 10.1515/geo-2016-0053 riods of Neogene Guantao and Minghuazhen Formations, Received Feb 14, 2016; accepted Jul 18, 2016 and migrated along major faults from source kitchens to reservoirs. The secondary faults acted as barriers, result- Abstract: The Dongying anticline is an E-W striking com- ing in the formation of fault-bound compartments. The plex fault-bounded block unit which located in the central high points of the anticline and well-sealed traps near sec- Dongying Depression, Bohai Bay Basin. The anticline cov- ondary faults are potential targets. This paper provides a ers an area of approximately 12 km2. The overlying succes- reservoir formation model of the low-order transfer zone sion, which is mainly composed of Tertiary strata, is cut by and can be applied to the hydrocarbon exploration in normal faults with opposing dips. In terms of the general transfer zones, especially the complex fault block oilfields structure, the study area is located in a compound transfer in eastern China. zone with major bounding faults to the west (Ying 1 fault) and east (Ying -8 and -31 faults). Using three-dimensional Keywords: transfer zone; fault kinematics; stress proper- seismic data, wireline log and checkshot data, the geome- ties; petroleum migration; Dongying Depression; Bohai tries and kinematics of faults in the transfer zone were Bay Basin; China studied, and fault displacements were calculated. The re- sults show that when activity on the Ying 1 fault dimin- ished, displacement was transferred to the Ying -8, Ying -31 and secondary faults so that total displacement in- 1 Introduction creased. Dynamic analysis shows that the stress fields in Transfer zones are important structural elements in exten- the transfer zone were complex: the northern portion was sional regions that are locate between normal faults [1–7]. a left-lateral extensional shear zone, and the southern por- Morley et al. classified transfer zones into synthetic, diver- tion was a right-lateral extensional shear zone. A model gent and convergent types according to the configuration of potential hydrocarbon traps in the Dongying transfer of the major faults (Fig. 1b, 1d, 1e) and into approaching, zone was constructed based on the above data combined overlapping, co-lateral and co-linear types based on the with the observed reservoir rock distribution and the seal- major fault terminations in planar view [1]. Through de- ing characteristics of the faults. The hydrocarbons were tailed studies of their structural style (Fig. 1a, 1b, 1c), dis- mainly expulsed from Minfeng Sag during deposition pe- placement transfer [9], and control on hydrocarbon distri- bution, transfer zones are believed to be the prior locations for the development of hydrocarbon reservoirs [8–11]. The *Corresponding Author: Fei Tian: Key Laboratory of Petroleum transfer zones are located at a relatively high position, can Resources Research, Institute of Geology and Geophysics, Chi- connect disparate structural units within a basin or sub- nese Academy of Sciences, Beijing, China, 100029; School of basin, develop many small faults as reservoir traps and Geosciences, China University of Petroleum, Qingdao, Shan- dong, China, 266580; Email: [email protected]; Tel: may control palaeo-drainage patterns, resulting in the de- (86) 18500507515 position of coarse-grained sediments that may form reser- Jianting Yang: Shengli Oilfield Branch Co., SINOPEC, Dongying, voir rocks for hydrocarbons [12–14]. Shandong Province, China, 257061 Previous studies have focused on large-scale trans- Ming Cheng, Yuhong Lei, Likuan Zhang: Key Laboratory of fer zones between major faults at a basin or sub-basin Petroleum Resources Research, Institute of Geology and Geo- scale [15–17]. However, few studies have investigated these physics, Chinese Academy of Sciences, Beijing, China, 100029 Xiaoxue Wang, Xin Liu: Research Institute of Exploration & De- structures at a more local scale, although relatively mi- velopment, Tarim Oilfield Company PetroChina, Korla, Xinjiang, nor faults may have a significant influence on hydrocar- China, 841000 © 2016 F. Tian et al., published by De Gruyter Open. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. Compound transfer zone in Dongying anticline Ë 613 Figure 1: Common transfer zone geometries in extensional regions. (a) (b) (c) are the plain view, three-dimensional view and profile sec- tions, respectively, of a synthetic–overlapping transfer zone. (d) Divergent-overlapping transfer zone, with the major faults dipping away from each other. (e) Convergent-overlapping transfer zone, with the major faults dipping towards each other. (f) Convergent-overlapping and synthetic-overlapping compound transfer zone, summarized by the Dongying transfer zone, based on [1]. bon distribution [18]. The Dongying anticline in the Bo- convergent-overlapping transfer zone (Fig. 1e). Thus, the hai Bay Basin has a complex structure. Over 35 normal Dongying structure is referred to as a compound transfer faults are located within a 12 sq. km area in which E- zone (Fig. 1f). This paper presents a reservoir model for the W, N-S and NW-SE striking faults converge. The Ying 8, Dongying structure and provides a theoretical basis for fu- -31 and -1 faults bound the anticline and control the lo- ture exploration activities in this area and in other similar cal structure, and numerous lower-order faults are also complex fault blocks. present. Because oil was discovered in the Dongying an- ticline in 1964, many relatively small-scale oil accumula- tions in fault blocks have been discovered, and there are 2 Geological background approximately 430 million barrels of oil in reserves [19]. To effectively develop the oilfield, the Dongying an- The Dongying anticline is located in the central portion ticline has been divided into a number of discrete fault of the Dongying Depression (Fig. 2c). The Dongying De- blocks. Reservoir units in these fault blocks have a medium pression is part of the Jiyang sub-basin, located in the SE to high water cut [20], and enhancing oil recovery is a con- Bohai Bay Basin (eastern China). The Dongying Depres- tinuous challenge. Structural studies have shown that a sion is bound by the Chen-Jiazhuang Uplift to the north, convergent-overlapping transfer zone is present between the Qingtuozi Uplift to the east, the Luxi-Guangrao Up- the Ying 1 and Ying 8 faults [21]. However, a lack of under- lift to the south, and the Linfanjia-Binxian Uplift to the standing of the complex relationships between the fault west (Fig. 2c). It measures 90 km east-west by 65 km north- block units has caused a low success ratio in recently south, and covers an area of 5700 km2 [22]. drilled wells. This paper attempts to analyse the geometry and kine- matics of faults in the Dongying fault block using three- 2.1 Stratigraphy dimensional (3D)seismic data, wireline logging data, well tops and checkshot data. Structurally, southern por- The Dongying Depression is filled with a thick Ceno- tion of the area is an E-W striking synthetic-overlapping zoic sedimentary succession that comprises the Paleogene transfer zone (Fig. 1b),and the northern portion forms a 614 Ë F. Tian et al. Figure 2: (a) Location map of Bohai Bay basin. (b) The subunits of Bohai Bay Basin, including Liaohe, Liaodong Bay, Bozhong,Jiyang Huanghua, Jizhong, and Linqing subbasins. The Dongying Depression locationed in the east part of Jiyang subbasin. (c) Secondary struc- tural units and oilfield distributions in the Dongying Depression.(d) A N-S structural cross section with the main fault systems, and theloca- tion is shown in (c) h-h’. Modified from [17]. Kongdian (Ek), Shahejie (Es) and Dongying (Ed) Forma- conformity, which is the main regional unconformity in tions; the Neogene Guantao (Ng) and Minghuazhen (Nm) the Dongying Depression. Above the unconformity, the flu- Formations; and the Quaternary Pingyuan (Qp) Formation vial and deltaic Guantao and Minghuazhen Formations (Fig. 3) [18, 19, 21]. were deposited and dominated by mudstones and sand- The Kongdian Formation was deposited on top of the stones. (or over the) Mesozoic. It consisted primarily of red mud- stones with thin red sandstones, and deposited in a flu- vial and shallow-lake environment [24]. Above the Kong- 2.2 Fault Framework dian Formation is the Shahejie Formation, which is widely distributed in the faulted depression, but it is nearly ab- Bordered by a dominant north-bounding graben fault, the sent on structural highs and depression edges. The Shahe- Dongying anticline forms an asymmetrical half graben jie Formation is dominantly lacustrine, containing mainly (Fig. 2d), typical of many graben structures in eastern source rocks and sandstone reservoir rocks, and is divided China. Multiple Mesozoic and Cenozoic faults, which con- into four members (Es4, Es3, Es2 and Es1 from base to trolled the structural framework and depositional process top). The Dongying Formation, which is developed in a in the depression, are the key factors for structure units fan delta and shallow lacustrine environment, consists of and sedimentary units [23]. The faults are categorized into sandstones interbedded with mudstones and is an impor- orders depending on their scale (extent and throw) and tant reservoir in the depression. Uplift and erosion follow- structural characteristics. First-order normal faults are the ing the deposition of Ed resulted in a major regional un- Chennan and Gaoqing-Pinnan faults (Fig. 2c 1 , 2 ), which Compound transfer zone in Dongying anticline Ë 615 Figure 3: Generalized Paleogene-Quaternary stratigraphy of the Dongying Depression, showing main sedimentary facies and the major U petroleum system elements, including the Es3 and Es4 source rocks, and multiple reservoirs mainly in Es3 and Ed Formations.
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