Carbonate sealing and its controlling factors: cap rock and inner barrier layers of Yingshan Formation on Tazhong Northern Slope, Tarim Basin
The Yingshan Formation, located on the Tazhong Northern Slope, contains oil- and gas-rich layers with the reserves of about 700 × 106 TOE. The high-resistivity inner layers isolate the hydrocarbon bearing zones and form the sequential sets of reservoir bed-seal assemblages in a vertical direction within the Yingshan Formation, which is directly bound above by a micritic carbonate cap rock that is overlain by the 3rd to 5th members of the Lianglitag Formation. The sealing capability of the cap rock and inner barrier layers was evaluated macroscopically and microscopically in terms of the core breakthrough pressure and thin-section identification. The evaluation parameters were extracted from the statistical analysis of drilling and logging data. The 3rd to 5th members of the Lianglitag Formation are more shaly, but the inner barrier layers in the Yingshan Formation are more dolomitic. Argillaceous limestone is more capable of sealing oil and gas zones than micritic limestone. The 3rd to 5th members of the Lianglitag Formation, of which the gamma ray response and core displacement pressure are greater than 20 API and 14 MPa, respectively, provide good sealing with thicknesses of more than 100 m and have better sealing with thickness of more than 200 m. For the same porosity, dolomite has lower coreflood displacement pressure than limestone. The difference in coreflood displacement pressure between the barrier layers and the underlying reservoir bed is 6 MPa, the cutoff value for sealing capability. Carbonate sealing was controlled by early sedimentation and was influenced by late diagenesis. The direct cap rock is dense and has cement content of more than 10%, up to 31%. The reservoir bed has cement content of less than 10%. Generally, the direct cap rock and the inner barrier layers are relatively stable on the lateral distribution.
Anahtar Kelimeler:
Carbonate cap rock, displacement pressure, sealing ability, Tazhong Northern Slope, Yingshan Formation
Carbonate sealing and its controlling factors: cap rock and inner barrier layers of Yingshan Formation on Tazhong Northern Slope, Tarim Basin
The Yingshan Formation, located on the Tazhong Northern Slope, contains oil- and gas-rich layers with the reserves of about 700 × 106 TOE. The high-resistivity inner layers isolate the hydrocarbon bearing zones and form the sequential sets of reservoir bed-seal assemblages in a vertical direction within the Yingshan Formation, which is directly bound above by a micritic carbonate cap rock that is overlain by the 3rd to 5th members of the Lianglitag Formation. The sealing capability of the cap rock and inner barrier layers was evaluated macroscopically and microscopically in terms of the core breakthrough pressure and thin-section identification. The evaluation parameters were extracted from the statistical analysis of drilling and logging data. The 3rd to 5th members of the Lianglitag Formation are more shaly, but the inner barrier layers in the Yingshan Formation are more dolomitic. Argillaceous limestone is more capable of sealing oil and gas zones than micritic limestone. The 3rd to 5th members of the Lianglitag Formation, of which the gamma ray response and core displacement pressure are greater than 20 API and 14 MPa, respectively, provide good sealing with thicknesses of more than 100 m and have better sealing with thickness of more than 200 m. For the same porosity, dolomite has lower coreflood displacement pressure than limestone. The difference in coreflood displacement pressure between the barrier layers and the underlying reservoir bed is 6 MPa, the cutoff value for sealing capability. Carbonate sealing was controlled by early sedimentation and was influenced by late diagenesis. The direct cap rock is dense and has cement content of more than 10%, up to 31%. The reservoir bed has cement content of less than 10%. Generally, the direct cap rock and the inner barrier layers are relatively stable on the lateral distribution.
Keywords:
Carbonate cap rock, displacement pressure, sealing ability, Tazhong Northern Slope, Yingshan Formation,
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- Alekseev AS, Kononova LI, Nikishin AM (1996). The Devonian and Carboniferous of the Moscow Syneclise (Russian Platform): stratigraphy and sea-level changes. Tectonophysics 268: 149–168.
- Alsharhan AS, Nairn AEM (1997). Sedimentary Basins and Petroleum Geology of the Middle East. Amsterdam, the Netherlands: Elsevier.
- Bai GP (2007). A preliminary study of main control factors on oil and gas distribution in Persian Gulf Basin. J China Univ Petrol 31: 28–32 (in Chinese).
- Beydoun ZR (1988). The Middle East: Regional Geology and Petroleum Resources. Beaconsfield, UK: Scientific Press. 600
- Lin CS, Yang HJ, Liu JY, Rui ZF, Cai ZZ, Li ST, Yu BS (2012). Sequence architecture and depositional evolution of the Ordovician carbonate platform margins in the Tarim Basin and its response to tectonism and sea-level change. Basin Res 24: 559–582.
- Lu XS, Jiang YL, Song Y (2007). Influence of mechanical properties and stress state of caprock on its sealing performance: taking Kela-2 gas field as an example. Nat Gas Ind 27: 48–51 (in Chinese).
- Lü Y, Zhang SC, Wang YM (2000). Research of quantitative relations between sealing ability and thickness of cap rock. Acta Petrolei Sin 21: 27–30 (in Chinese).
- Lü YF, Fu G (1996). The Sealing of Oil/Gas Reservoir. Beijing, China: Petroleum Industry Press (in Chinese).
- Macgregor DS (1986). The hydrocarbon systems of North Africa. Mar Petrol Geol 13: 329–340.
- Mei MX, Zhang H, Meng XQ, Chen YH (2006). Sequence stratigraphic division and framework of the Lower Cambrian in the Upper Yangtze region. Geol China 33: 1292–1304 (in Chinese).
- Parsons MB, Azgaar AM, Curry JJ (1980). Hydrocarbon occurrences in the Sirte Basin, Libya. CSPG Memoir 6: 723–732.
- Peterson JA, Clarke JW (1983). Petroleum Geology and Resources of Volga-Urals Province, USSR. Alexandria, VC, USA: US Geological Survey.
- Proust JN, Chuvashov BI, Vennin E, Boisseau T (1998). Carbonate platform drowning in a foreland setting: the Mid-Carboniferous Platform in Western Urals (Russia). J Sediment Res 68: 1175– 1188.
- Qin J, Ge L, Chen YM, Kang H, Liu Y (2011). Reservoir prediction of Lower Triassic Feixianguan Formation in Jiannan Area, Sichuan Basin. Mar Origin Petrol Geol 16: 9–17 (in Chinese).
- Sun ML, Liu GD, Li J (2008). Features of cap rocks of gas pools and criteria of identification. Nat Gas Ind 28: 36–38 (in Chinese).
- Tian NX, Chen WX, Huo H, Tian JB, Wu J (2008). Petroleum geology characteristics and play prediction in the Sirte Basin, Libya. Oil Gas Geol 29: 485–490 (in Chinese).
- Watts NL (1987). Theoretical aspects of cap-rock and fault seals for single and two-phase hydrocarbon columns. Mar Petrol Geol 4: 274–307.
- Wu GH, Chen ZY, Qu TL, Wang CH, Li HW, Zhu HY (2012). Characteristics of the strike-slip fault facies in Ordovician carbonate in the Tarim Basin, and its relations to hydrocarbon. Acta Geol Sin 86: 119–227 (in Chinese).
- Wu GH, Li QM, Zhang BS, Dong LS, Zhang YG, Zhang HQ (2005). Structural characteristics and exploration fields of No. 1 Faulted Slope Break in Tazhong area. Acta Petrol Sin 26: 27–30 (in Chinese).
- Xu ZY, Zhang GJ (2001). Divisional method and characteristic analysis of impermeable barrier layers in carbonate rock formation. J China Univ Petrol: 46–50 (in Chinese). 601
- ISSN: 1300-0985
- Yayın Aralığı: Yılda 6 Sayı
- Yayıncı: TÜBİTAK
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