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The Main Controlling Factors of Glutenite Development and Their Impacts on Oil Energy Extraction

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The Main Controlling Factors of Glutenite Development and Their Impacts on Oil Energy Extraction energies Article The Main Controlling Factors of Glutenite Development and Their Impacts on Oil Energy Extraction Yuping Wang 1,* , Chunmei Dong 1, Chengyan Lin 1 and Qingjie Hou 2,3 1 School of Geosciences, China University of Petroleum, Qingdao 266580, China; [email protected] (C.D.); [email protected] (C.L.) 2 Geophysical Research Institute, Sinopec Shengli Oilfield Company, Dongying 257022, China; [email protected] 3 Working Station for Postdoctoral Scientific Research, Shengli Oilfield, Dongying 257000, China * Correspondence: [email protected] Abstract: The glutenite reservoirs discovered in the Jiyang depression in Bohai Bay contribute greatly to proven oil and gas resources, which have reached 1.27 billion cubic meters. Both insufficient studies on the glutenite distribution and incomplete understanding of the corresponding geology restrict further oil energy extraction. Hence, it is necessary to study the controlling factors of glutenite development. Sedimentation, tectonic faults, geophysical data, etc., was used in this paper to study these factors. Four main controlling factors involved in the development of glutenite fan bodies have been studied and summarized: the fault ramp controls the glutenite fan, the fault characteristics control the glutenite acreage, the fault throw controls the thickness of the glutenite, and the dimensions of the incised valleys control the glutenite transport capacity. Based on this geological understanding, this paper analyzes the relationship between oil productivity data and the factors controlling conglomerate development. With this, the reservoir in the study area is divided into a high production area, medium production area, and low production area. The C913 well was Citation: Wang, Y.; Dong, C.; Lin, C.; deployed in the predicted high production area. The daily oil production reached 88 t/d, and the Hou, Q. The Main Controlling Factors energy exploitation effect was good. Therefore, this study provides important guidance for the of Glutenite Development and Their further extraction of oil energy. Impacts on Oil Energy Extraction. Energies 2021, 14, 1807. https://doi. Keywords: main controlling factors; incised valley; fault throw; glutenite; oil production org/10.3390/en14071807 Academic Editor: Hemanta Sarma 1. Introduction Received: 20 February 2021 The glutenite body is a kind of block-like geological rock body, which is composed Accepted: 23 March 2021 Published: 24 March 2021 of sandstone or conglomerate [1,2]. The glutenite reservoirs have a variety of rock types, such as sandstone, conglomerate, muddy conglomerate, sandy mudstone, etc. It can be Publisher’s Note: MDPI stays neutral developed as a single fan body or a group of fans superimposed together, and is usually with regard to jurisdictional claims in developed in the steep slope zone of a continental faulted. The genetic types of glutenite published maps and institutional affil- include nearshore subaqueous fan, alluvial fan, turbidite fan, fan delta, etc. The seismic iations. reflection of glutenite is strong amplitude in the top surface boundary, low frequency inside, and no obvious stratification. Glutenite oil and gas reservoirs are generally close to their provenance and have many development stages [3]. The reservoirs usually have large thicknesses, high productivity per unit area, and great exploration potential [4]. The lithol- ogy of glutenite reservoirs changes rapidly, the reservoir connectivity is difficult to describe, Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. and exploration and development are difficult [5–8]. Therefore, to predict the distribution This article is an open access article of glutenite bodies, it is first necessary to systematically study the characteristics and distributed under the terms and control factors of glutenite development. conditions of the Creative Commons The Chezhen Sag has the characteristics of a typical continental faulted lake basin in Attribution (CC BY) license (https:// China. Its steep slope zone glutenite is extremely well developed. The oil and gas resources creativecommons.org/licenses/by/ are approximately 150 million tons and form the main target for the next exploration [9]; 4.0/). however, since exploration began in 1996, only a few exploratory wells have obtained Energies 2021, 14, 1807. https://doi.org/10.3390/en14071807 https://www.mdpi.com/journal/energies Energies 2021, 14, 1807 2 of 16 economical oil production, which forms a large contrast with the excellent accumulation background. For example, the actual average daily oil production of the failed wells CD3 and GX13 is only 0.1 t/d.This may be due to the unclear distribution of glutenite bodies and unclear factors controlling development. Many scholars have analyzed the con- trolling factors for the development of glutenite fans and determined that the distribution of glutenite fans is mainly influenced by factors such as paleostructure, paleoclimate, fluc- tuations in lake level, and hydrodynamic forces [10,11]. At present, the control mechanism of these conventional factors on the development of glutenite bodies is relatively clear, but research work has found that the Chezhen Sag is rich in fault assemblages and fan types, and their controlling factors have not been systematically studied by scholars. This paper takes the glutenite body in the Guojuzi area of the Chezhen Sag as an example, studies the correlations of various characteristic parameters of the glutenite body distribution with the fault fan combination type, incised valley thickness and depth, and systematically explains the development of the glutenite. On the basis of the geological study, this paper links the main control factors of glutenite with the actual production of petroleum energy, and also provides a guidance to promote the oil production. 2. Geological Background 2.1. Location and Strata The Chezhen Sag is a secondary depression in the northern part of the Jiyang De- pression in the Bohai Bay Basin; to the east is the Zhanhua Depression, to the west is the Qingyun Uplift, to the south are the Wudi Uplift and Yihezhuang Uplift, and to the north is the Chengzikou Uplift (Figure1). The Chezhen Sag is a rift-like continental basin with a narrow distribution from north to south and extends from east to west. The Guojuzi Sag is located in the Northeastern Chezhen Sag. The main faults include the Da 34 fault, Dawang Beida 35 nose structure, Guo 6 East fault, Chengdong Uplift, and secondary Energies 2021, 14, x FOR PEER REVIEW 3 of 16 depressions divided by the Guo 4 and Guo 2 faults; Guojuzi is one of the three sub-sags in the Chezhen Sag. Figure 1. TheFigure geographical 1. The geographical location and location geological and geological structure structure of the study of the studyarea. area. The Paleogene strata in this area are divided into the Kongdian Formation, Shahejie Formation, and Dongying Formation from bottom to top (Figure2). The glutenite mainly developed in the Shahejie Formation. The Shahejie Formation is divided into members 1, 2, 3, and 4 vertically. The fourth member is dominated by beach bar sand deposits in shallow lakes, the third member is dominated by nearshore underwater fans in deep lake and semideep lake environments, the second member is dominated by shallow beach bar Figure 2. Stratigraphic development characteristics (Es1, Es2, Es3, and Es4 are short for members 1, 2, 3, and 4 in Shahejie Formation Eocene). 2.2. Types of Glutenite Fans In the northern steep slope zone of the Guojuzi area, various types of glutenite fans, such as alluvial fans, fan deltas, nearshore underwater fans, and turbidite fans, are widely developed (Figure 3). The remaining resources were approximately 220 million cubic meters, which were suitable for exploration. Important targets are alluvial fans, which are the products of weathering and denudation of parent rock carried by seasonal currents. They are fan-shaped deposits formed in locations where the slope of the terrain becomes gentler [12,13]. The alluvial fan is divided into fan root, fan middle, and outer Energies 2021, 14, 1807 3 of 16 deposits, and the first member is mainly developed in semideep lakes. Most submarine fans are deposited near the shore. The 2nd and 3rd members of the Shahejie Formation are the main layers where nearshore subaqueous fans of glutenite have developed. Figure 2. Stratigraphic development characteristics (Es1, Es2, Es3, and Es4 are short for members 1, 2, 3, and 4 in Shahejie Formation Eocene). 2.2. Types of Glutenite Fans In the northern steep slope zone of the Guojuzi area, various types of glutenite fans, such as alluvial fans, fan deltas, nearshore underwater fans, and turbidite fans, are widely developed (Figure3). The remaining resources were approximately 220 million cubic meters, which were suitable for exploration. Important targets are alluvial fans, which are the products of weathering and denudation of parent rock carried by seasonal currents. They are fan-shaped deposits formed in locations where the slope of the terrain becomes gentler [12,13]. The alluvial fan is divided into fan root, fan middle, and outer fan. The braided rivers are present in the middle fan, where the reservoir with high porosity and permeability [14–16]. Fan deltas are fan-shaped deposits formed from high sediment inputs into stable water bodies. They are mainly composed of fan delta plains, fronts, and front fan deltas. Fan delta plains and fronts develop branch channels with high porosity and permeability; front fan deltas are mainly composed of silty clay, which consists of sandy clay and has poor physical properties [17–19]. Nearshore underwater fans are gravity flow fans in which sediments directly enter the deeper waters of lakes, and most of their deposits are close to steep banks [20,21]. According to the differences in the provenance supply capacity, these fans can be divided into thick layers and thin layers. The thick layers have well-developed fan roots but poorly developed fan middle sections and fan margins; thin-layered fan bodies have well-developed interlayers, while glutenite has Energies 2021, 14, x FOR PEER REVIEW 4 of 16 fan.
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