تأثير العمليات التحويرية على تطور مسامية الصخور المكمنية لتكوين قره جيني في شمالي وشمال غربي العراق

Abstract

This paper describes the diagenetic processes, it products and how affected on porosity of succession of Kurra Chine Formation. Four oil wells selected in northern and north eastern Iraq, which are represented by: Jabal Kand (JK-1), Ain Zalah (AZ-29), Butmah (Bm-15) and Alan (Aa-2). Petrographic study shows that the diagenetic processes have a large effect on petrophysical properties of formation successions, especially porosity and permeability. Cementation, compaction, replacement and recrystallization are main processes to porosity reduction. About the enhancement of porosity, dolomitization, dissolution and sometime recrystallization are considered the main diagenetic processes to increase the porosity. According to the Carbonate pore systems classification of [1], porosity in Kurra Chine Formation was divided into two main groups: Interparticle (intergrain and intercrystal) and vuggy pores. Dependence on particle size and sorting, the Interparticle pore space is subdivided into three petrophysical classes. Class1 is the least common fabric in the four section study while class2 is common and very important because it contains bituminous material. Class3 is very common but have lowest reservoir Importance, except that dolomitizated. Vuggy porosity is subdivided into two types depended on how the vugs are interconnected: separate vug and touching vug. Moldic and intragrain pores are the most abundant of separate vug pores within formation successions. Touching vug pores represented by fractures, microfractures and fenestral.