Using Kriginglogging To Interpret And Evaluate Property Of Clastic Rock Reservoir

There is abundant finely sandstone gas in China,but designedly and systemicresearch on low permeable finely gas started fairly late.Recently years,geologists haveaccumulatedrich and valuable experience through developing and exploring tightreservoir of Central Plains,Sichuan and Changqing fields.Compared with normalreservoir,porosity of tight sandstone reservoir is lower than5%-12%generally,textureof pores is complex,and its space consists of distributional micro holes.It also has thefeatures that poor physical properties,connectivity and permeability,throat mainly isbelt bend capillary pore or long flake.What’s more.water saturation and capillarypressure gradient are higher than normal reservoir.All the factors above make it harderto exploration.While appropriate well logging interpretation can beneficial laterexploration and development,we need more study on the research of tight sandstonereservoir.It’s also the key and difficult point of domestic and foreign geology studyfield.There are a lot of problems need to research and resolve.This paper is based on the theory that forecast reservoirparameter distributionthroughkriging,taking space geometric parameter(x,y) as two electrical parameters（AC,SH）,thus geologists can utilize kriging technology to analysis the propertycomposition of electrical property and physical property,and the linear dimensionforecast of physical property,that is well logging interpretation.There are three advantages of using this method to interpret well logging:①It can better reflect the nonlinear structure between electrical and physicalproperties.②Kriging prediction equation can better reflect the nonlinear relationshipbetween electrical and physical properties.③Kriging prediction can give each predictive value a standard deviation and evaluate prediction accuracy by depth.While ordinary logging interpretation equationcan only use interrelation coefficient to evaluate model accuracy.On the basis of previous treating well logging and core property, first analyzingand evaluating variation function texture of electric property and physicalproperty,thereby,researching texture geology meaning.After that, distributing kriging andestablishing number pattern of electric property and physicalproperty,discussingpattern’s application on reservoir evaluation.then,on the ground of pattern,interpretlogs,well logging.At the same time,compare with other normal well logginginterpretation method to evaluate the rationality and accuracy of new predictionmethod. In the end,forecasting and evaluating porosity distribution of Hebaochangarea.This kind of logging method not only can interpret and evaluate well loggingprobably,but also has better accuracy on interpretation.Therefore,it’s the first time to apply this method on well logging interpretationand it’s a new attempt on well logging field of kriging.Meanwhile,it undertakessuperior risk and difficulty but also has widespread application prospect.