| In recent years,the exploration shows that multiphase igneous rocks have been developed in Suqiao Wen'an,Nanmeng,Longhuzhuang and Zhongchakou and Niubei slope of Jizhong depression.The oil reservoirs have been found in the adjacent clastic rock reservoirs,and some of the igneous rock test shows low-yield oil stream,but the overall scale of the oil field is small.The analysis shows that when igneous rock is used as reservoir,the evidences of oil and gas is mostly poor,and the wells used as reservoir are very few.While the igneous rock as barrier bed plays a positive role in the storage of clastic rock reservoir.Therefore,on the basis of extensive collection and analysis of previous research results,based on the geology of petroleum,principles of seismic exploration,petrology of igneous rock,combined with the collected data of seismic,geophysical logging,drilling and coring,analysis and test data,this paper makes a comprehensive study on the petrological characteristics,period and distribution characteristics,reservoir types,the relationship between igneous rocks and clastic rocks,and the accumulation model of igneous rocks in Wen'an slope of Jizhong depression.It will provide theoretical and technical support for the implementation of secondary fine exploration in oil fields.According to the microscopic observation and analysis of igneous rock slices on the Wen'an slope,there are three types of igneous rocks on the Wen'an slope,namely basalt,diabase and tuff.The basalts are mostly gray-black with a porphyritic texture,and the phenocrysts are platelike basic plagioclase and pyroxene;the main constituent minerals are basic plagioclase,alkaline feldspar and pyroxene.The diabase has a diabase texture and embedded crystal contains a long texture;the main components are pyroxene,plagioclase,a small amount of magnetite,and occasionally apatite and pyrite.The tuff is mainly composed of volcanic ash and a small amount of shard and crystal frangments.The crystal frangments are mainly quartz and plagioclase,with stoma and almond shaped structure.The almonds are filled with chlorite.Most of the volcanic ash has been devitrified and argillated,and carbonate metasomatism has been observed.According to the well log and seismic data,the igneous rocks in the Sha 1 member and Sha 2 member of Wen'an slope are divided into periods,and studied on the distribution of igneous rock in the Sha 1 member,Sha 2 member and Sha 3 member.The igneous rocks of the Sha 1 member and the Sha 2 member are divided into 12 stages by the combination of well and seismic,in which the Sha 2 member corresponds to the I-V stage,the lower Sha 1member corresponds to the VI-IX stage,and the upper Sha 1 member corresponds to the X-XII stage.By analyzing the distribution characteristics of igneous rocks in each stage,the distribution of igneous rocks of the II stage is the widest,and the igneous rocks of the VIII stage are the thickest.The igneous rocks of the Sha 3 member are widely distributed in the Wen'an slope,and they are distributed in NE-SW direction.The thickness of the igneous rocks gradually decreases eastwards,and the thickness is roughly between 1-197 m.Combined with seismic data,well logging comprehensive interpretation data and oil test data,the elaborate anatomy of reservoir was performed in the Wen'an slope area.There were six types of clastic rock reservoirs in the Wen'an slope area.Among them,fault block reservoir,lens reservoir and fault lithologic reservoir are independent of igneous rock.The other three types are igneous rock truncation oil reservoir,igneous rock overlying oil reservoir,and igneous rock lateral barrier oil reservoir.The analysis shows that the configuration relationship between igneous rock and clastic rock reservoir is igneous rock truncation the clastic rock reservoir,sandstone overlying the igneous rock and the igneous rock laterally keep out the clastic rock reservoir.Based on the results of oil reservoir anatomy,the overall accumulation model of the Wen'an slope is analyzed.The results show that the hydrocarbon accumulation in the Wen'an slope area is mainly caused by the step migration from depression to slope under the guidance of fault and sand layer.Igneous rock blocks the reservoir in the process of hydrocarbon accumulation,the hydrocarbon migration and accumulation step model is formed with igneous rock as barrier. |
PDF Full Text Request