Electrical responses and classification of complex waterflooded layers in carbonate reservoirs: A case study of Zananor Oilfield, Kazakhstan

Experiments of electrical responses of waterflooded layers were carried out on porous,fractured,porous-fractured and composite cores taken from carbonate reservoirs in the Zananor Oilfield,Kazakhstan to find out the effects of injected water salinity on electrical responses of carbonate reservoirs.On the basis of the experimental results and the mathematical model of calculating oil-water relative permeability of porous reservoirs by resistivity and the relative permeability model of two-phase flow in fractured reservoirs,the classification standards of water-flooded layers suitable for carbonate reservoirs with complex pore structure were established.The results show that the salinity of injected water is the main factor affecting the resistivity of carbonate reservoir.When low salinity water(fresh water)is injected,the relationship curve between resistivity and water saturation is U-shaped.When high salinity water(salt water)is injected,the curve is L-shaped.The classification criteria of water-flooded layers for carbonate reservoirs are as follows:(1)In porous reservoirs,the water cut(fw)is less than or equal to 5%in oil layers,5%–20%in weak water-flooded layers,20%–50%in moderately water-flooded layers,and greater than 50%in strong water-flooded layers.(2)For fractured,porous-fractured and composite reservoirs,the oil layers,weakly water-flooded layers,moderately water-flooded layers,and severely water-flooded layers have a water content of less than or equal to 5%,5%and 10%,10%to 50%,and larger than 50%respectively.

Seismic risk evaluation for a planning mountain tunnel using improved analytical hierarchy process based on extension theory

Seismic risk evaluation(SRE) in early stages(e.g., project planning and preliminary design)for a mountain tunnel located in seismic areas has the same importance as that in final stages(e.g.,performance-based design, structural analysis, and optimization). SRE for planning mountain tunnels bridges the gap between the planning on the macro level and the design/analysis on the micro level regarding the risk management of infrastructural systems. A transition from subjective or qualitative description to objective or quantitative quantification of seismic risk is aimed to improve the seismic behavior of the mountain tunnel and thus reduce the associated seismic risk. A new method of systematic SRE for the planning mountain tunnel was presented herein. The method employs extension theory(ET)and an ET-based improved analytical hierarchy process. Additionally, a new risk-classification criterion is proposed to classify and quantify the seismic risk for a planning mountain tunnel. This SRE method is applied to a mountain tunnel in southwest China, using the extension model based on matter element theory and dependent function operation.The reasonability and flexibility of the SRE method for application to the mountain tunnel are illustrated.According to different seismic risk levels and classification criteria, methods and measures for improving the seismic design are proposed, which can reduce the seismic risk and provide a frame of reference for elaborate seismic design.

Morphological differentiation characteristics and classification criteria of lunar surface relief amplitude

Lunar landforms are the results of geological and geomorphic processes on the lunar surface.It is very important to identify the types of lunar landforms.Geomorphology is the scientific study of the origin and evolution of morphological landforms on planetary surfaces.Elevation and relief amplitude are the most commonly used geomorphic indices in geomorphological classification studies.Previous studies have determined the elevation classification criteria of the lunar surface.In this paper,we focus on the classification criteria of the topographic relief amplitude of the lunar surface.To estimate the optimal window for calculating the relief amplitude of the lunar surface,we use the mean change-point method based on LOLA(Lunar Orbiter Laser Altimeter)Digital Elevation Model(DEM)data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera(SELENE TC).The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar landforms.Taking the topographic relief amplitudes of 100 m,200 m,300 m,700 m,1500 m and 2500 m as thresholds,the lunar surface is divided into seven geomorphic types,including minor microrelief plains(<100 m),minor microrelief platforms[100 m,200 m),microrelief landforms[200 m,300 m),small relief landforms[300 m,700 m),medium relief landforms[700 m,1500 m),large relief landforms[1500 m,2500 m)and extremely large relief landforms(≥2500 m).The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins,while the minor microrelief platforms are mainly in the transition regions between the maria and highlands.The microrelief landforms are mainly located in regions with relatively high topography,such as wrinkle ridges and sinuous rilles in the mare.The small relief landforms are mainly scattered in the central peak and floor fractures of craters.The medium relief landforms are mainly distributed in the transition regions between crater floors and crater walls,between crater walls and crater rims,between basin floors and basin walls,and between basin walls and basin rims.Large and extremely large relief landforms are mainly found along crater walls and basin walls.The classification criteria determination for assessing lunar surface relief amplitude described in this paper can provide important references for the construction of digital lunar surface geomorphology classification schemes.