Three-dimensional characterization of karstic dissolution zones, fracture networks, and lithostratigraphic interfaces using GPR cubes, core logs, and petrophysics: Implications for thief zones development in carbonate reservoirs

被引:11
|
作者
Lopes, Juliana A. G. [1 ]
Medeiros, Walter E. [1 ,2 ,3 ]
Oliveira, Josibel G. [2 ,3 ]
Santana, Flavio L. [2 ,3 ,5 ]
Araujo, Renata E. B. [1 ]
La Bruna, Vincenzo [1 ,2 ]
Xavier, Milton M. [1 ,2 ,3 ]
Bezerra, Francisco H. R. [1 ,4 ]
机构
[1] Univ Fed Rio Grande do Norte, Postgrad Program Geodynam & Geophys, Natal, Brazil
[2] Univ Fed Rio Grande do Norte, Dept Geophys, Natal, Brazil
[3] Natl Inst Sci & Technol Petr Geophys, CNPq, INCT GP, CAPES, Natal, Brazil
[4] Univ Fed Rio Grande do Norte, Dept Geol, Natal, Brazil
[5] Univ Fed Rio Grande do Norte, PRH 42 ANP, Natal, Brazil
关键词
Karstified reservoirs; Reservoir analogues; Karstic dissolution; Thief zones; Super-K layers; 3D GPR; GROUND-PENETRATING RADAR; TAHE OIL-FIELD; POTIGUAR BASIN; JANDAIRA FORMATION; BISCAYNE AQUIFER; OUTCROP ANALOGS; BOREHOLE IMAGES; FLUID-FLOW; POROSITY; PERMEABILITY;
D O I
10.1016/j.marpetgeo.2023.106126
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Fractures and karstic dissolution features have been recognized to significantly affect subsurface fluid flow on a range of scales in carbonate rocks. However, due to the information gap between seismic and borehole scales, characterizing these features is a real challenge. We present a three-dimensional multidisciplinary approach to identify the main factors controlling the formation of connected rock volumes composed by permeable karstic dissolution zones. We investigate two outcrops in the Jandaira Formation, which is an intensely fractured and karstified carbonate platform in the Potiguar Basin, Brazil. Two GPR cubes are jointly interpreted with cored boreholes, borehole images, petrophysical profiles, and thin sections. We verified that attenuated zones of GPR signal are related to secondary carbonate changes caused by fracturing and/or diagenetic alterations, leading to the development of relatively high secondary permeability. At least three types of attenuation/karstic zones might occur: fractured or broken zones affected by fracture enlargement due to dissolution, zones submitted to intense diagenetic alterations, and void spaces as a final end-member of these two processes. Fractures are preferential routes to fluid flow, thus contributing to increase dissolution processes, particularly in layers having relatively high values of primary matrix porosity and permeability. On the other hand, relevant diagenetic al-terations might occur in layers that contain high concentration of stylolites. As a result of interconnecting dis-solved stylolites, zones of relatively high secondary permeability can be created regardless of the primary values of matrix porosity and permeability. Geobodies of connected volumes of karstic zones often present tabular shapes and are delimited by subvertical fractures and subhorizontal lithostratigraphic interfaces. In the reservoir scale, these tabular geobodies might compose highly connected permeable volumes of altered carbonate rocks that constitute thief zones or super-K layers.
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页数:21
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  • [1] Three-dimensional characterization of karstic dissolution zones, fracture networks, and lithostratigraphic interfaces using GPR cubes, core logs, and petrophysics: Implications for thief zones development in carbonate reservoirs
    Lopes, Juliana A.G.
    Medeiros, Walter E.
    Oliveira, Josibel G.
    Santana, Flávio L.
    Araújo, Renata E.B.
    La Bruna, Vincenzo
    Xavier, Milton M.
    Bezerra, Francisco H.R.
    Marine and Petroleum Geology, 2023, 150