The Evaluation Method Researches On Ordovician Mud Fractured-vuggy Carbonate Reservoir In The Northern Of The Tarim Basin

The ordovician carbonate reservoirs locating in northern of Tarim Basin bury deeply, have complex types, and strong heterogeneity. With the influence of the late sedimentary structure, the carbonate fractured-vuggy reservoirs are filled with mud, sand and limestone breccia so that the logging evaluation is very diffcult.Base on the previous work,this paper aims to study the logging evaluation method as to the fractured-vuggy reservoirs which are filled. Because of the clay particle is small and its adsorption performance is strong, that the pore of reservoir can be filled with shale easily. The conductivity of clay is stronger than that of sand and limestone breccia, so it can effect the logging seriously. Consquently, this paper focuses on studing the method of logging effective evaluation of the fractured-vuggy reservoir filled with mud and researching the evaluation method of fluid property.As to the validity evaluation of the mudded fractured-vuggy carbonate reservior, it is cardinal to judge the degree of the fractured-vuggy reservoir filled with mud. Effectiveness criteria on the mud fractured-vuggy reservoir is not easy to establish, this paper mainly studies the effectiveness of the mud cave, the reservoir filled completely is invalid, and that filled partly is valid. The main idea of the paper is to distinguish the valid reservoir and the invalid one by making full use of the logging data, the drilling data,and the well testing data,etc. Adopting intersection technology with the logging parameters or postprocess parameters of fractured-vuggy reservoir which have judged their validity, choose the parameters which lead a better effect. Consider these parameters as the standard to evaluate the effectiveness of the other reservoir,so that the validity of the inconclusive reservoir can be estimated. Finally, using the production logging data to verify the validity result of the fractured-vuggy reservoir filled with mud.In order to determine the filling degree of clay, the logging parameters (such as the natural gamma ray value, the uranium gamma value, the deep lateral resistivity value, the shallow lateral resistivity value and the clay content through many mineral components of calculation analysis program)which can be influenced by the mud and the porosity parameters (the density logging value, the acoustic time logging value, the neutuon log value and the porosity calculated by pore curves) intersect. Through the intersection method, with natural gamma ray value for x-coordinate, with the product (also named conventional apparent formation water resistivity) of deep lateral resistivity and porosity value for y-coordinate, we can get a linear discriminant function to distinguish the validity of the fractured-vuggy reservoir filled with mud. This method can generally estimate the validity of the fractured-vuggy reservoir, and only exits seldom abnormal points. It has a good effect in the research area.As to the evaluation method of fluid property, it is essential to remove the additional conduct influence of clay on the resistivity logging value. Adopt the conventional apparent formation water resistivity method to identify the fluid property. Using the redefined conventional apparent formation water resistivity to study the fluid property in Block6and Block7of TaHe oil field, and set up the fluid property estimate standard. The fluid property evaluation method of the fractured-vuggy carbonate reservoir with mud is based on that of the fracure-vuggy reservoir with pure limestone. Through many mineral components analysis program to calculate the clay content, choose the linear conduct model to correct the additional conductivity of clay. Using the intersection technology, the mean and variance of the conventional apparent formation water resistivity of the reservoir with mud which has well testing data intersect. The result can generally distinguish the oil-gas and water of the fractured-vuggy reservoir with mud. At last, taking use of the fluid property evaluation method to estimate the well which has no well testing data. The method has a good effect in the research area.