Reservoir Development And Distribution Characteristics Of The Contact Metamorphic Zones In Shuaiduo-Maoshan Area,Qintong Sag

The study on the characteristics and control factors of subvolcanic rocks contact metamorphic zones is of great significance for the exploration and development of magmatic oil reservoirs.In this paper,the contact metamorphic zones of the shallow subvolcanic rocks are taken as the research object,which develop in Shuai duo-Maoshan area of Qin Tong depression,Subei basin.Systematic core and flake observation,well logging interpretation and borehole-seism-modulus integration techniques are conducted to evaluate spatial distribution regularities and dissect the characteristics of reservoir development in typical contact metamorphic zones.Based on this,the favorable contact metamorphic zones in the subvolcanic rocks of Qingtong Sag are predicted.The study shows that the wall rocks are altered by subvolcanic rocks,forming the contact zone reservoir of subvolcanic rocks.The contact metamorphic zones shows high gamma,medium acoustic,medium spontaneous potential and high resistivity on the log curve.Moreover,the extent of contact metamorphic zones primarily are affected by the thickness of subvolcanic rocks.The contact metamorphic zones are generally distributed in two sides of the subvolcanic rocks and have a positive correlation with the thickness of the subvolcanic rocks.The upper contact metamorphic zones develop thicker than the lower contact metamorphic zones.There are 3 types of hydrocarbon reservoirs in the typical contact metamorphic zones,including contact alteration,fault shielding and volcanic channel shelter.In addition,the thickness of altered mudstone in contact metamorphic zones are the main factor affecting the distribution of high quality reservoirs,and the high-quality reservoirs in the contact metamorphic zonse near the volcanic channel are the favorable areas for hydrocarbon accumulation.