The deep strata in the Ledong area of the Yinggehai Basin have a complex pressure structure.As indicated by the surveyed pressure data,strata at different depths and horizons have greatly different pore pressure.Especially in the Huangliu Formation,the pore pressure shows a large transverse span.Moreover,it tends to reduce at the top but rises rapidly at the bottom,with a pressure coefficient of up to 2.3,indicating the presence of significant pressure mutation.Pressure prediction using only the undercompaction model yields large errors and thus is prone to induce engineering accidents.To effectively predict the formation pressure,it is necessary to determine the genetic mechanisms of overpressure.This study effectively identified the genetic mechanisms of the overpressure using the cross plots of vertical effective stress vs logging response.The identification results show that the genetic mechanisms of the deep overpressure in the Ledong area mainly include mechanical unbalanced compaction,chemical compaction,vertical pressure transmission along faults,and hydrocarbon-generating pressurization.A proper pressure prediction method was established based on the defined genetic mechanisms,thus improving the prediction precision and ensuring the smooth construction of drilling engineering.
艾能平, 宋鹏, 李伟, 吴云鹏, 李虎. 莺歌海盆地乐东区深层异常高压成因机制及预测研究[J]. 物探与化探, 2023, 47(1): 190-198.
AI Neng-Ping, SONG Peng, LI Wei, WU Yun-Peng, LI Hu. Genetic mechanisms and prediction of the deep abnormal high pressure in the Ledong area,Yinggehai Basin. Geophysical and Geochemical Exploration, 2023, 47(1): 190-198.
Guo L Z, Zhong Z H, Wang L S, et al. Regional tectonic evolution around Yinggehai basin of south China sea[J]. Geological Journal of China Universities, 2001, 7(1):1-12
Fan C W. Tectonic deformation features and petroleum geological significance in Yinggehai Large Strike-Slip Basin,south China sea[J]. Petroleum Exploration and Development, 2018, 45(2):190-199.
Xie X N, Liu X F. Related to black shale seriesfluid dynamic system and relationship with accumulation of hydrocarbon in overpressured basin[J]. Bulletin of Mineralogy Petrology and Geochemisty, 2000, 19(2):103-108
Wan Z F, Xia B, Ling G, et al. Hydrocarbon accumulation model for overpressure basin:An example from the Yinghehai basin[J]. Marine Geology & Quaternary Geology, 2010, 30(6):91-97.
Zhang Q M, Liu F N, Yang J H. Overpressure system and hydrocarbon accumulation in the Yinggehai basin[J]. China Offshore Oil and Gas:Geology, 1996, 10(2):65-75.
Liu A Q, Fan C W, Wu Y P, et al. Study on prediction method of allochthonous pressure based on transfer mode in high temperature and high pressure field of south China sea[J]. China Offshore Oil and Gas, 2021, 33(1):50-55.
Hu Y T, Liu T, Chen X J, et al. Application of comprehensive evaluation technology of formation pressure while drilling in ultra-high pressure wells in Yinggehai basin[J]. Journal of Yangtze University:Natural Science Edition, 2019, 16(10):29-33.
Zhao J Z, Li J, Xu Z Y. Advances in the origin of overpressures in sedimentary basins[J]. Acta Petrolei Sinica, 2017, 38(9):973-998.
doi: 10.7623/syxb201709001
[10]
Bowers G L. Pore pressure estimation from velocity data:Accounting for overpressure mechanisms besides under compaction[C]// IADC/SPE27488,IADC/SPE Drilling Conference, 1994:515-530
[11]
Ramdhanam, Goulty N R. Overpressure-generating mechanisms in the peciko field,lower kutai basin,indonesia[J]. Petroleum Geoscience, 2010, 16(4):367-376.
doi: 10.1144/1354-079309-027
[12]
Goulty N R, Sargent C, Andras P, et al. Compaction of diagenetically altered mudstones Part 1:Mechanical and chemical contributions[J]. Marine and Petroleum Geology, 2016, 77:703-713.
doi: 10.1016/j.marpetgeo.2016.07.015
[13]
Tingay M R P, Morley C K, Laird A, et al. Evidence for overpressure generation by kerogen to gas maturation in the Northern malay basin[J]. AAPG Bulletin, 2013, 97(4):639-672.
doi: 10.1306/09041212032
[14]
Van Ruth P, Hillis R, Tingate P. The origin of overpressure in the carnarvon basin,western australia:Implications for pore pressure prediction[J]. Petroleum Geoscience, 2004, 10(3):247-257.
doi: 10.1144/1354-079302-562
[15]
Fertl W H. Abnormal formation pressure:Implication to exploration,drilling,and production of oil and gas resources[M]. Amsterdam:Elsevier, 1976:382.
[16]
Magara K. Compaction and fluid migration,practical petroleum geology[M]. Amsterdam:Elsevier, 1978:319.
[17]
Luo X R, Vasseur G. Contributions of compaction and aquathermal pressuring to geopressure and the influence of environmental conditions[J]. AAPG Bulletin, 1992, 76(10):1550-1559.
[18]
Osborne M J, Swarbrick R E. Mechanisms for generating overpressure in sedimentary basins:A reevaluation[J]. AAPG Bulletin, 1997, 81(6):1023-1041.
[19]
Audet D M. Mathematical modeling of gravitational compaction and clay dehydration in thick sediment layers[J]. Geophysical Journal International, 1995, 122:283-98.
doi: 10.1111/j.1365-246X.1995.tb03554.x
Li C, Luo X R, Fan C W, et al. Generation mechanism of overpressure and its implication for natural gas accumulation in Miocene reservoir in Ledong A structrure,Ledong slope,Yinggehai Basin[J]. Chinese Journal of Geology, 2011, 56(4):1034-1051.
[21]
Lahann R W, Swarbrick R E. Overpressure generation by load transfer following shale framework weakening due to smectite diagenesis[J]. Geofluids, 2011, 11(4):362-375.
doi: 10.1111/j.1468-8123.2011.00350.x
[22]
Goulty N R, Ramdhan A M, Jones S J. Chemical compaction of mudrocks in the presence of overpressure[J]. Petroleum Geoscience, 2012, 18(4):471-479.
doi: 10.1144/petgeo2012-018
Li C, Luo X R, Zhang L K. Overpressure responses for chemical compaction of mudstones and the pore pressure prediction[J]. Journal of China University of Mining & Technology, 2020, 49(5):851-968.
Liu X F, Xie X N. Review on formation mechanism of the reservoir overpressure fluid system[J]. Geological Science and Technology Information, 2003, 22(3):55-60.
[27]
Luo X R, Vasseur G. Geopressuring mechanism of organic matter cracking:Numerical modeling[J]. AAPG Bulletin, 1996, 80(6):856-874.
Xie Y H. Models of pressure prediction and new understandings of hydrocarbon accumulation in the Yinggehai Basin with high temperature and super-high pressure[J]. Natural Gas Industry, 2011, 31(12):21-25.
[29]
Bowers G L. Pore pressure estimation from velocity data:Accounting for overpressure mechanisms besides undercompaction[J]. SPE Drilling and Complection, 1995, 10(2):89-95.
