Elemental geochemistry of the Upper Cretaceous reservoir and surrounding formations applied in geosteering of horizontal wells, Lebăda Field – Western Black Sea

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2020-12-17 DOI:10.2516/ogst/2020083

I. Prundeanu, C. Chelariu, David Rafael Contreras Perez

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引用次数: 3

Abstract

The precise landing and steering of horizontal wells using conventional mudlogging and Logging While Drilling (LWD) data is a particular challenge for the Lebăda Field, offshore Romania. The use of a new technique of elemental geochemistry analysis (or chemosteering) became an option for the identification of Cenomanian, Turonian–Coniacian–Santonian, Campanian and Eocene strata. This has enabled more accurate placement of the horizontal development wells within the desired reservoir target interval. Geochemical data enabled the identification of chemostratigraphic zones C1, C2, C3 and zone R that correspond to the reservoir section. The application is a result of the geochemical zonation performed using elements and ratios that are sensitive to depositional environment, sea level change, heavy mineral concentrations and siliciclastic input namely: Sr/Ca, Zr/Th, Si/Zr and Si/K. In ascending stratigraphic order, the ratio thresholds of zone C3 are Zr/Th > 11, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19, while zone R corresponds to 5.5 < Zr/Th < 11, Sr/Ca < 1.1, Si/Zr > 22 and Si/K > 19. C2 zone is defined by Zr/Th < 5.5, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19 and C1 zone is characterized by Si/Zr > 22 and Si/K > 19. The selected geochemical ratios indicate a strong geochemical zonation. In the case of offset wells, 85.9% of the data confirmed the proposed classification and 89.4% for the real-time application case. The zone R shows a strong contrast with the surrounding formations facilitating critical decisions during well placement and geosteering, increasing the reservoir exposure by 28%. The quantitative approach delivered very valuable results, providing a solid foundation to define correlation and well landing intervals. Simultaneously, the cost of the method represents a fraction of the LWD cost and 0.15% of the total project cost, making it very cost effective and a standard approach for future projects.

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黑海西部leb油田上白垩统储层及周围地层元素地球化学在水平井地质导向中的应用

利用常规泥浆测井和随钻测井(LWD)数据进行水平井的精确着陆和导向，对于罗马尼亚海上的leb油田来说是一个特别的挑战。元素地球化学分析(或化学导向)的新技术成为识别Cenomanian、turonian - conisian - santonian、Campanian和Eocene地层的一种选择。这使得水平开发井能够更精确地定位在期望的油藏目标层段内。地球化学资料识别出与储层剖面相对应的C1、C2、C3和R化学地层带。该应用是利用对沉积环境、海平面变化、重矿物浓度和硅屑输入敏感的元素和比例进行地球化学分带的结果，即:Sr/Ca、Zr/Th、Si/Zr和Si/K。从地层升序看，C3带比值阈值为Zr/Th > 11、Sr/Ca > 1.1、Si/Zr < 22、Si/K < 19, R带对应比值阈值为5.5 < Zr/Th < 11、Sr/Ca < 1.1、Si/Zr > 22、Si/K > 19。C2区以Zr/Th < 5.5, Sr/Ca > 1.1, Si/Zr < 22, Si/K < 19为特征;C1区以Si/Zr > 22, Si/K > 19为特征。选取的地球化学比值显示出强烈的地球化学分带性。在邻井的情况下，85.9%的数据证实了所提出的分类，89.4%的数据证实了实时应用情况。R区与周围地层形成强烈对比，有助于在井位和地质导向过程中做出关键决策，使储层暴露度增加28%。定量方法提供了非常有价值的结果，为定义相关性和井的着陆间隔提供了坚实的基础。同时，该方法的成本只占随钻测井成本的一小部分，占项目总成本的0.15%，因此非常具有成本效益，是未来项目的标准方法。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.