Dolomitization Process of C-4 to F Members of the Qum Formation and its Effect on Reservoir Qualit

Document Type : Research Paper

Authors

Abstract

Petrographic studies on samples of C-4 to F members of Qum Formation shows that dolomitization is one of the most important diagenetic processes affecting carbonate members. Despite this fact that the dolomitization process is one of main reasons for developing porosity and reservoir properties, in section under study, reservoir properties are totally poor and matrix porosity is low. The distribution of dolomicrite and dolomicrosparite has mainly outspreaded the matrix porosity in a limited distance; much of the dolomite in this section is partial dolomitization. The development of cement (mainly dolomitic cement) in deep burial depth as filling the pore, the high percentage of dolomitization formed intertwined mosaics, compaction, stylolitization, and illitization closing the pore throat and reducing porosity and permeability caused reservoir property to become poor. Microscopic studies revealed the presence of 9 types of dolomite, four models of dolomitization in Qum Formation in this section, including Sabkha model, the leakage model, deep burial model, and Do-Rag model. Upper Red Formation on the Qum Formation and the presence of clay and marl in Qum Formation as a combination of clay are the main sources of Mg supply for the Qum Formation dolomites.
 

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[1]. Friedman G. M., “Terminology of crystallization textures and fabrics in sedimentary rocks”, Jour. Sed. Petrology, 35, pp. 643-655., 1965.##
[2]. Sibley D. F. and Gregg J.M.,“Classsification of dolomite rock texture”, Jour. Sed. Petrology, 57,pp. 967-975., 1987.##
[3]. Mazzullo S. J., “Geochemical and neonorphic alteration of dolomite: a review. Carbonate and evoporites”, pp. 21-37, 1992.##
4. آدابی م.، ژئوشیمی رسوبی، چاپ اول، نشر آرین، 448ص.، 1383.##
[5]. Ye. Q., and Mazzullo S. J., “Dolomitization of lower permian platform facies”, Wichia Formation, north platform, Midland Basin” Texas, Carbonates and Evaporites, 8, pp. 55-70., 1993.##
[6]. Adabi N. H., and RaoC. P., “Petrographic, element and isotopic criteria for Central Iran”, Iran Petrol. Inst. No. 15, pp.561-574. The recognition of carbonate mineralogy and climates during the Jurassic (e.g.form Iran and England): 13th Geol. Conv. Australia, (Abst), p.6., 1996.##
[7]. Gregg J. and Sibley D. E., “Epigenetic dolomitization and the origin of xenotopic dolomite texture”, Jou. Sed. Petrology, 54, pp. 908-931., 1984.##
[8]. Macneil A. J., and Jones B., “Dolomitization of pedro castle formation (pliocen), Cayman Brac, British West Indies. Sed. Geol.164, pp. 216-238, 2003.##
[9]. Sellwood B. W., Scoot J., James B., and Evans R., “Regional significance of dolomitization in the Great Oolite reservoir facies of southern England”, in J. Brooks, and K.W. Glennie, Petroleum Geology of North west Europe London: Graham and Trotman, pp.129-137., 1987.##
[10]. Adams A. E. and Rhodes M. L. “Dolomitization by seepage refluxion”, Bull. Am. Asso. Petrol. Geology. Vol. 44, pp.1912-1920, 1960.##
[11]. امرائی ج.، دیاژنز و ژئوشیمی بخش‌های آهکی سازند قم در ناحیه قم (مقاطع نرداقی، دوچاه، دوبرادر و کمرکوه)، دانشگاه تربیت معلم، پایان‏نامه کارشناسی ارشد، 1384.##
[12]. Wanless H. R., “Limestone response to stress, pressure solution and dolomitizatin”, Jou. Sed. Petrology, Vol. 49, pp. 437-442, 1979.##
[13]. Hannover, “Petrographical Study Yortesha-e-3(Ys#3)”, Vol. 2, Lab Investigation of the Aquifer Exploration Well, Kavrene Buuand Betrieps .GMBH. Co. 1999.##
[14]. http:// dx.doi.org/10.1130/G32923.1, Trude, T.Geomar, Helmholtz center for ocean research, Geology, 2012##