碳酸岩分散有机质的基本存在形式、演化特征与碳酸岩地层油气评价

MAIN FORMS OF DISSEMINATED ORGANIC MATTER IN CARBONATE ROCKS, THEIR EVOLUTIONARY CHARACTERISTICS AND SIGNIFICANCE IN OIL-GAS EVALUATION

Two major characters are recognized with respect to the evolution of organic matter during diagenesis of carbonate rocks; (1) expellation of organic matter from carbonate minerals through crystallization, which could reduce the amount of organic matter significantly in the early stage of diagenesis; (2) protection of organic matter by the minerals, especially in the late stage of diagenesis. According to their nature and relations to the protection during diagenesis, three majer forms of disseminated organic matter in carbonate rocks can be distinguished: adsorbed, ctystallization-trapped organic matter and organic inclusions. Owing to the protection by minerals the maturation process of disseminated organic matter proceeds very slowly, and the matority of crystallization-trapped organic matter may play an important role in carbonate source rocks. Most of the organic inclusions are migrated organic matter, such as hydrocarb ons; so organic inclusions may be a good indicator which can be used to study the primary,secondary migration and the concentration of oil and gas in carbonate source rocks and carbonate reservoir strata,

Two major characters are recognized with respect to the evolution of organic matter during diagenesis of carbonate rocks: (1) expellation of organic matter from carbonate minerals through crystallization, which could reduce the amount of organic matter significantly in the early stage of diagenesis; (2) protection of organic matter by the minerals, especially in the late stage of diagenesis.According to their nature and relations to the protection during diagenesis, three majer forms of disseminated organic matter in carbonate rocks can be distinguished: adsorbed, crystallization-trapped organic matter and organic inclusions. Owing to the protection by minerals the maturation process of disseminated organic matter proceeds very slowly, and the maturity of crystallization-trapped organic matter may play an important role in carbonate source rocks. Most of the organic inclusions are migrated organic matter, such as hydrocarb ons; so organic inclusions may be a good indicator which can be used to study the primary, secondary migration and the concentration of oil and gas in carbonate source rocks and carbonate reservoir strata.