Evaluation of dolomite reservoirs in the Longwangmiao Formation, Lower Cambrian in Northern Sichuan basin, China

Abstract

With the extended petroleum exploration of the carbonate reservoir in the Longwangmiao Formation, Lower Cambrian in Sichuan basin, looking for a new favorable exploration area is the primary task in current exploration. This paper focusing on the dolomite reservoir in the Longwangmiao Formation in the Northern Sichuan basin, will evaluate the reservoir conditions, including reservoir lithology, reservoir spaces, physical properties and other basic characteristics. Combined with sedimentary environment study and diagenesis analysis, the genetic mechanism of Longwangmiao reservoir in study area will be discussed. It indicates that the reservoir rocks of Longwangmiao Formation in the study area are composed of dolarenite and crystalline dolomite, and the main reservoir spaces are intergranular dissolved pores, intragranular dissolved pores and intercrystalline dissolved pores. However, most of dissolved pores have been filled with bitumen, which lead to the reservoir properties very poor, both the porosity and permeability are worse than that of central Sichuan basin, so the reservoir in the Longwangmiao Formation in the Northern Sichuan basin is low-porosity and low-permeability reservoir. During the Early Cambrian Longwangmiao period, the study was near the old-land, and the energy of sea water was not enough to deposit many grain shoals, which cause the sediments are small with lots of quartz and muds. Moreover, because lacking of large scale karstification in the late diagenesis, there isn't much dissolved pores and vugs develop in the Longwangmiao Formation. Some Intergranular dissolved pores and intercrystalline dissolved pores formed by the early atmosphere water dissolved exist as some reservoir spaces, but most of them have been filled with bitumen, which was residual when the ancient oil reservoir transformed. Above factors cause the Longwangmiao Formation in the Northern Sichuan basin become not a very favorable reservoir in Sichuan basin.

Keywords

Reservoir evaluation / Dolomites / Longwangmiao Formation / Northern Sichuan basin

Acknowledgement

This research was Supported by scientific research starting project of SWPU (No. 2017QHZ005) and open Fund of Shandong Provincial key laboratory of Depositional mineralization (No. DMsMzO1TO35)

References

[1] J.H. Du, C.N. Zou, C.C. Xu, H.Q. He, P. Shen, Y.M. Yang, Y.L. Lei, G.Q. Wei, Z.C. Wang, Y. Yang, Theoretical and technical innovations in strategic discovery of huge gas fields in Longwangmiao Formation of central Sichuan paleo-uplift, Sichuan Basin, Pet. Explor. Dev. 41 (3) (2014) 1e10 (in Chinese with English abstract).

[2] C.C. Xu, P. Shen, Y.M. Yang, B. Luo, J.Z. Huang, X.F. Jiang, J.R. Xie, Y.J. Cen, Accumulation conditions and enrichment patterns of natural gas in th lower Cambrian Longwangmiao Fm reservoirs of the Leshan-Longnüsi Paleohigh, Sichuan Basin, Nat. Gas. Ind. 34 (3) (2014) 1e7 (in Chinese with English abstract).

[3] M.D. Jin, X.C. Tan, L. Li, et al., Characteristics and distribution of grain bank of the Lower Cambrian Longwangmiao Formation in Moxi-Gaoshiti area, Sichuan Basin, JOPC 17 (3) (2015) 347e358 (in Chinese with English abstract).

[4] X.F. Yang, X.Z. Wang, H. Tang, et al., Research sedimentary microfacies of the Longwangmiao Formation in moxi area, central Sichuan Basin, Acta Sedimentol. Sin. 33 (5) (2015) 972-982.

[5] T. Ma, X.C. Tan, L. Li, et al., Sedimentary characteristics and distribution of grain shoals in the lower cambrian Longwangmiao Formation of Sichuan Basin and its adjacent areas, J. Palaeogeogr. 17 (2) (2015) 213-228.

[6] J.M. Du, B.M. Zhang, Z.C. Wang, et al., Sedimentary model and reservoir genesis of dual grain banks at the Lower Cambrian Longwangmiao Fm carbonate ramp in the Sichuan Basin, Nat. Gas. Ind. 36 (6) (2016) 1-9.

[7] J.M. Song, S.G. Liu, Y.H. Zhao, et al., Characteristics and sedimentary geological significant of Lower-Middle Cambrian tempestites in central Sichuan basin, Acta Pet. Sin. 37 (1) (2016) 13-25.

[8] Yao Genshun, Zhou Jingao, Zou Weihong, et al., Characteristics and distribution rule of Lower Cambrian Longwangmiao grain beach in Sichuan Basin, Mar. Orig. Pet. Geol. 22 (3) (2013) 1-7.

[9] S.G. Gao, Z.M. Hu, W.G. An, et al., Distribution characteristics of dolomite reservoir pores and caves of Longwangmiao Formaiton gas reservoirs in the Sichuan basin, Nat. Gas. Ind. 34 (3) (2014) 103-109.

[10] M.D. Jin, W. Zeng, X.C. Tan, et al., Characteristics and controlling factors of beach-controlledkarst reservoirs inLongwangmiaoFormation,Moxi-Gaoshiti area, Sichuan Basin, NW China, Pet. Explor. Dev. 41 (6) (2014) 650-660.

[11] X.F. Yang, X.Z. Wang, H. Tang, et al., The Caledonian paleokarstification of Longwangmiao Formation, Lower Cambrian in the central Sichuan basin, China, Carbonates and Evaporites 32 (3) (2017) 325-335.

[12] X.F. Yang, X.Z. Wang, Y.M. Yang, et al., Diagenesis of the dolomite reservoir in Lower Cambrian Longwangmiao Formation Formation in central Sichuan basin, Geol. Sci. Technol. Inf. 34 (1) (2015) 35-41.

[13] Tian Yanhong, Liu Shugen, Zhao Yihua, Song Jinmin, Song Linke, Sun Wei, et al. Diagenesis of Lower Cambrian Longwangmiao Formation reservoirs in central area of Sichuan Basin, China J. Chengdu Univ. Technol. Sci. Technol. Ed. 41 (6) (, 2014) 671-683.

[14] X.F. Yang, X.Z. Wang, H. Tang, et al., Dolomitization by Penesaline sea water in Early Cambrian Longwangmiao Formation, Central Sichuan basin, China, J. Earth Sci. 28 (2) (2017) 305-314.

[15] J.G. Zhou, C.C. Xu, G.S. Yao, G. Yang, J.Y. Zhang, Y. Hao, F. Wang, L.Y. Pan, M.F. Gu, W.Z. Li, Genesis and evolution of lower Cambrian Longwangmiao Formation reservoir, Sichuan Basin, SW China, Pet. Explor. Dev. 42 (2) (2015) 158e166 (in Chinese with English abstract).

[16] Liu Shugen, Song Jinmin, Zhao Yihua, Zhong Yong, Song Linke, Tian Yanhong, et al. Controlling factors of formation and distribution of Lower Cambrian Longwangmiao Formation high quality reservoirs in Sichuan Basin, China J. Chengdu Univ. Technol. Sci. Technol. Ed. 41 (6) (, 2014) 657-670.

[17] X.F. Yang, X.Z. Wang, H. Tang, et al., Reservoir characteristics and main controlling factors of the Longwangmiao Formation in the Moxi area, central Sichuan Basin, China, Arab. J. Geosci. 9 (3) (2016).

[18] Y.L. Li, F.R. Wu, D.J. Liu, et al., Distribution rule and exploration prospect of the Longwangmiao Fm reservoirs in the Leshan-Longnüsi Paleouplift, Sichuan Basin, Nat. Gas. Ind. 34 (3) (2014) 61e66 (in Chinese with English abstract).

[19] J.Y. Zhang, W.J. Luo, J.G. Zhou, et al., Main origins of high quality reservoir of Lower Cambrian Longwangmiao Formation in the giant Anyue gasfield, Sichuan basin, SW China, Nat. Gas. Geosci. 26 (11) (2015) 2063-2074.

[20] Hao Meng, Ying Ren, Zhong Dakang, et al., Geochemical characteristic and its paleoen-vironmental implication of Cambrian Longwangmiao Formaiton in eastern Sichuan Basin, China, Nat. Gas. Geosci. 27 (7) (2016) 1299-1311.

[21] Y. Ren, D.K. Zhong, C.L. Gao, et al., Sedimentary facies of the Longwangmiao Formation in Eastern Sicuan basin and its adjacent area, J. Paleogeogr. 17 (3) (2015) 335-346.

[22] Y. Ren, D.K. Zhong, C.L. Gao, et al., Characteristics and controlling factors of the Lower Cambrian Longwangmiao Formation reservoirs in easternSichuan Basin and its adjacent areas, J. Paleogeogr. 17 (6) (2015) 829-840.

[23] Ying Ren, Zhong Dakang, Chonglong Gao, Xueqi Yang, Rui Xie, Zhuopei Li, Minxin Deng, Yongcheng Zhou, Geochemical characteristics, genesis and hydrocarbon significance of dolomite in the Cambrian Longwangmiao Formation, eastern Sichuan Basin, Acta Pet. Sin. 37 (9) (2016) 1102-1115.

[24] K.W. Yin, S.G. Liu, J.M. Song, et al., Mixed Sedimentation features of the Middle and Lower Cambrian, Nanjiang Area, Northern Sichuan Basin, Nat. Gas Technol. Econ. 8 (6) (2014) 5-8.

[25] C.L. Mou, W. Liang, K.K. Zhou, et al., Sedimentary facies and paleogeography of the middle-upper Yangtze area during the Early Cambrian (Terreneuvian-series 2), Sediment. Geol. Tethyan Geol. 32 (3) (2012) 41-53.

[26] C. Fang, H.C. Li, J.G. Zhou, et al., The influences of sea-level changes on the quality of bank reservoirs of the Lower Cambrian Longwangmiao Formation, in the Gaoshiti-Moxi area, Sichuan Province, China, J. Nat. Gas Sci. Eng. 32 (2016) 292-303.

[27] W.M. Feng, J.Q. Liu, Y. Xie, et al., Upper-Yangtze Longwangmiao eage carbonate platform mode and hydrocarbon exploration, Spec. Oil Gas Reserv. 22 (1) (2015) 61-66.

[28] M.X. Mei, C. Zhang, H. Zhang, et al., Sequence stratigraphic framworks and their forming backgrounds of paleogeography for the Lower Cambrian of the Upper Yangtze region, Geoscience 20 (2) (2006) 195-208.

[29] W.M. Feng, Y. Xie, J.Q. Liu, et al., Sedimentary model and hydrocarbon exploration targets of the Lower Cambrian Longwnagmiao Formation in the Upper Yangtze area, Geol. Sci. Technol. Inf. 33 (3) (2014) 106-111.

[30] J.Z. Huang, S.J. Cheng, J.R. Song, et al., The hydrocarbon source system and the formation of large and medium gas fields in sichuan basin, Sci. China (Ser. D) 26 (6) (1996) 504-510.

[31] W.M. Huang, S.G. Liu, G.Z. Wang, et al., Geological conditions and gas reservoir features in Lower Paleozoic in Sichuan Basin, Nat. Gas. Geosci. 22 (3) (2011) 465-476.

[32] H.F. Yuan, M.X. Zhao, G.Z. Wang, et al. Phase of hydrocarbon migration and accumulation in Cambrian Longwangmiao Formation of Moxi structure, Central Sichuan basin, China, J. Chengdu Univ. Technol. Sci., Technol. Ed. 41 (6) (2014) 694-702.