Sweet Prediction Of Volcanic Reservoir Of Karagang Formation In Mazhong Area Of Malang Sag

With the discovery of the volcanic reservoir in the Niudong block of the Malang sag in the Santanghu Basin,the study of the nearby volcanic reservoirs and accumulation rules in the Mazhong area has become the focus of the next step.However,previous studies on volcanic facies distribution,the forming condition and the key controlling factor of the volcanic oil deposit is inadequate due to the volcanic reservoirs complicated controlling factors in the Mazhong area.For this reason,based on cores and rock slices,making full use of existing seismic,drilling,well logging and comprehensive geological data,combining petroleum geology with volcanic petrology and other theories and methods,and taking the study of volcanic reservoir characteristics and controlling factors as the main line,we make a detailed analysis of volcanic lithology and lithofacies characteristics in the area,depicts the plane distribution of volcanic lithofacies.The controlling factors and enrichment regularity of volcanic reservoirs in the study area are clarified,which provides a clear direction for further exploration.Primary summing-up:(1)There are two types of volcanic lava and pyroclastic rocks developed in the study area.The main lithologies are basic basalt and andesite,of which basalt is the most developed.(2)Three facies phases of the explosive facies,overflow facies and volcanic sedimentary facies are identified,and the corresponding logging and seismic facies characteristics are clarified.(3)By analyzing the single well facies and the well facies of volcanic rocks in the study area,The Karagang Formation in Mazhong area are divided into five period and the volcanic facies distribution map of each period are drawn.(4)The pore types of volcanic reservoirs in the study area are various,among which the dissolution pores and fractures are most developed,The reservoir as a whole belongs to low-porosity low-permeability grade,The key controlling factors of reservoir’s petrophysical property include structural cracking and weathering leaching.(5)It is clarified that the inherited ancient nose uplift,fault,weathering leaching and volcanic lithofacies are the main factors of the controlling the volcanic reservoirs in the study area.(6)Clearing the enrichment regularity of the volcanic reservoirs of the Karagang Formation in the Mazhong area,and predicteing the exact location of the sweet by combining the seismic attributes.