Authors:
Yanfeng Wang
1
;
Shuqin Wang
2
;
Jianxin Li
2
;
Wenqi Zhao
2
;
Weiqiang Li
2
and
Changhai Li
2
Affiliations:
1
CNPC Aktobe Munaigas JSC, China
;
2
PetroChina Research Institute of Petroleum Exploration and Development., China
Keyword(s):
Carbonate reservoir, dolomite type, porosity, permeability
Abstract:
Taking the Carboniferous KT-I reservoirs in the NT Oilfield in the eastern margin of the Caspian Basin as a case, this paper studies the petrology and physical properties of carbonate reservoirs using core data. The carbonate reservoirs in the study area were deposited in the platform environment. The limestone deposited has experienced multiple stages of diagenetic alteration, among which the dolomitization played an important role in improving the reservoir quality. The dolomites in the study area are diverse in type and are characterized by the development of eight types of dolomites, including foraminifer dolomite, fuzulinid dolomite, bioclastic dolomite, micritic dolomite, micritic-powdery dolomite, powdery dolomite and lime dolomite, and karst breccia dolomite. Different types of dolomite have different characteristics observed on thin sections, and the physical properties vary too. Foraminifera, fuzulinid and bioclastic dolomites belong to grain dolomite with obvious biologic
al characteristics, relatively high permeability and average permeability of more than 100mD. Micrite, micritic-powdery and powdery dolomites are crystalline dolomites which are composed of dolomite crystals arranged closely, and the average permeability is less than 35mD.
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