Seismic Lithology Modeling Of Salt Rock Layer And Interlayer In Jianghan Salt Cavern Gas Storage

Underground gas storage plays an important role in peak shaving and ensuring safe use of gas,the typical gas storage in the world has depleted oil and gas reservoirs,aquifers,salt caves and other types.The salt cavern gas storage is a method of using water to dissolve salt to form underground space to store natural gas,it has the characteristics of strong storage capacity,high working gas volume ratio and high production efficiency.There are many interlayers in the salt layer of Jianghan Salt Mine.The mineral composition is mainly dolomite,anhydrite,siltstone,etc.,which are difficult to dissolve and difficult to collapse.It has great influence on the scale of storage and storage.Therefore,it is particularly important to grasp the controllable penetration of the interlayer.The underground salt and brine resources in the Huangchang area of Qianjiang Depression are abundant,and it has the superior conditions for building underground gas storage.The previous cavity pilot test wells showed that,multiple sets of interlayers are stably developed in the salt-bearing strata of the Huangchang Salt Mine.The thickness of the single layer is up to 9m,and the content of dolomite is high,which has an adverse impact on the construction of gas storage.The paper takes the 13-16th salt layer of the second member of Qianjiang Formation in the Huangchang area as the research object,and makes full use of a large number of geological,seismic and drilling data and mature geological interpretation and modeling software such as Petrel,Landmark and Jason for seismic lithology prediction.Finely depicting the development scale and spatial distribution characteristics of the target salt layer and interlayer of the second member of Qianjiang Formation,and establishing a salt mine geological model to provide geological basis for gas storage salt dissolution cavity.The top and bottom interfaces of the target salt layer of the second member of Qianjiang Formation in the Huangchang area have strong reflection characteristics on the seismic section and can be identified and tracked in the whole area.The inter-salt mudstone interlayer in the target salt layer shows high-gamma,high-density and high-sound"three-high"characteristics on the logging curve,and three sets of marker interlayers are developed from the bottom up.The logging response of the salt rock formation is characterized by low gamma,low density,and low acoustic"three low"characteristics.The natural gamma value of the mudstone between the 13-15th salt layers is greater than 40 API,the density value is greater than 2.3g/cm~3,and the wave impedance value is greater than 10000g*m/(s*cm~3),otherwise it is the salt rock.The natural gamma value of mudstone between 15-16 th salt layers is greater than 30API,the density value is greater than 2.2g/cm~3,and the wave impedance value is greater than 9500g*m/(s*cm~3),otherwise it is the salt rock.The distribution law of acoustic value is not obvious,from the global aspect,the acoustic value of mudstone is higher than that of salt rock.The interlayer 1 and the interlayer 2 show clear on the wave impedance profile,the lateral spread is stable,and the interlayer 3 features are not obvious,the wave impedance difference between the 15th salt rock layer and the 16th salt rock layer is obvious.Three sets of stable development interlayers were clearly identified on the segmented inversion section,and the predicted thickness of the interlayer and the actual drilling layer thickness error were small.Each set of salt rock and interlayer in the geological model has a clear distribution and inheritance development.Each layer has a structural feature of north low and south high,and the north is inclined,the syncline feature in the north is obvious.The thickness of each interlayer is relatively thin,ranging from 3-8m,The thickness of Wang 59 Well is the largest,and the cumulative thickness reaches 17.8m.the thickness of Wangchu1,3,6,and 8 Well in central is the smallest,and the cumulative thickness is about 14m.The 16th salt rock layer has the largest overall thickness,and the thickness of a single rock layer reaches 60m.The thickness of the well Wang 39 is the largest,and the cumulative thickness reaches 107m.The thickness of the Huang 31 well in the southeast slope is the thinnest,and the cumulative thickness is 87.4 meters.