Study Characteristics Of The Ancient Buried Hill Carbonate Reservoirs In Shulu Depression

The existing exploration results show that the main strata is Buried hill carbonate,and have many types of reservoirs and the formation mechanism of reservoirs is complicate and diagenetic mechanism is unknown,heterogeneity of reservoirs developed,which add the difficulties to the next exploration and development in Shulu depression.This paper study on the space of reservoirs and the types of reservoirs on the Buried hill carbonate by the data of core and thin section and logging. The results show that reservoirs space can be divided into the dissolution of cavity,pore and fracture etc. The type of Buried hill carbonate reservoirs can be divided into the reservoir of karst fracture-cave system,reservoir of fracture and pore-fractured reservoir by the space of the reservoirs and their association. Connected with well logging information and logging data,this paper comprehensively analysis the Buried hill Reservoirs of all the wells in this region,it is suggested that the dominating reservoirs of pore and reservoirs of pore-fracture,besides, the significance of the solution cavern reservoirs less than the two above.This paper discusses the Shulu depression developmental characteristics of buried hill reservoir, reservoirs are developed the Jixian system of Wumishan Formation, Cambrian, Ordovician, missing Ordovician department system. The type characteristics of the reservoir rock, the reservoir is mainly composed of limestone and dolomite, from top to bottom, the dolomite reservoir occupied proportional increase in the thickness and dolomite not only fractured, but also can develop intergranular the porosity reservoir performance is better than limestone, it is the main reservoir of buried hill. Also buried hill reservoir space, buried hill carbonate reservoirs in a variety of reservoir space in different forms in combination with each other to form a complex and diverse combination of infiltration storage space. To sum up, including the three basic types of fractured slit pore and slit hole composite type. They determine the type of the buried hill reservoir of carbonate reservoirs, seepage conditions and capacity characteristics.This paper study on the diagenesis of Buried hill carbonate. The results show that the main diagenesis of the region contain cementation, silicification, pressure solution, dolomitization, dissolution, karstification and cataclasis. Simultaneously,this paper also study on the diagenesis development period. This paper mainly focuses on the karstification. The development and distribution of Buried hill carbonate reservoirs is primary controlled by the Early Hercynian karstification and Late Hercynian karstification in Shulu depression. Where covered by the Carboniferous strata in the structure subsags fracture area of Shulu is mainly dominated by Early Hercynian karstification, and where covered by the Mesozoic and slopes with Paleogene coverage area in the south of Shulu is dominated by Late Hercynian karstification. The main reservoirs are the reservoir of karst fracture-cave system, the development of which is controlled by the Early Hercynian karstification.In this paper, the study of reservoir properties, Shulu depression reservoir nature to make in-depth study. Do a complete analysis of the physical properties of the area as a whole, not only in the longitudinal direction of the changes in the thickness of the reservoir and development characteristics of changes in physical properties, reservoir performance and lithology and depth of the relationship; also in the area plane analysis of the physical properties of different tectonic zone differences of reservoir properties factors. Of the reservoir fractures versus depth, reservoir fractures and pores relationship between porosity fractured reservoir development and clay content, lithology reservoir set performance changes with the depth of the relationship and the nature of the fracture development system of statistics and description. To accurately determine the slope zone and tectonic fault zone Diagenesis development, significant differences in the controlling factors of reservoir performance.Researching on the combine characteristics of Buried hill carbonate reservoirs and seal, the results suggest that the regional seal is the Carboniferous strata in the structure subsags fracture area, the directly capping is the slope tertiary mudstone and the triassic strata. Combine characteristics of reservoirs and seal in different regions is variable, the best in is the west near Ningjin convex slope with Shahejie where the Upper Wumishan Formation and Cambrian is conserved; in the central slope tertiary mudstone where the Upper Ordovician, has the best combine characteristics of reservoirs and seal; in the east of the structure subsags fracture area where C-P directly covering on the top of Ordovician, the combine characteristics of reservoirs and seal is poor.In this thesis, by logging, core, and analysis of laboratory data, clarify the baried hill carbonate of aperture hole with reservoir lithology、physical properties and reservoir space, statistical analysis of fracture-cave system distribution and developm law, explore the reservoir of diagenetic times and contr factors. Preferred the reservoir evaluation paramenters, to predict high-quality reser distribution. The application of fracture style analysis, the development of tectonic fractures, analysis of palaeogeomorphology, ancie sedimentary analysis with variety of analytical methods and results, to carry out a comprehensive evaluation of the buried hill reservoir multi-parameter forecast.By the study of the formation mechanism or development and distribution or controlling factors or evaluation of the reservoirs, it is shows that the west near Ningjin convex slope is the favorable area, and the central slope zone is the beneficial area, while where the east structure subsags fracture C-P area conserved is poor.