The Carbonate Reservoir Logging Evaluation Of Jiannan Region

Jiannan structure is located in West of Hubei and East of Sichuan where the hydrocarbon reservoirs have been successively found in Triassic system, Permian system and Carboniferous system from the 1960s to early the 1980s. In recent years, in the wake of the petroleum industry's development and increased demand for natural gas, the exploration and study of this region has been renewed since 2000.Most of wells in Jiannan region were completed in the 1960s and the 1970s with the logging suite being mainly the lateral resistivity logs early and the additional laterolog-3, acoustic log, hole temperature and fluid density late. Since the renewed exploration of the region, a batch of new wells have been completed in succession. The logging suites include the logs of three resistivities, three porosities, stratigraphic dip and DBHC in these wells, among which in two wells even the electrical micro-imaging data and dipole shear wave data have been taken, thereby to greatly increase the logging information and to lay foundation for the in-depth comprehensive geological analysis in this region.The reservoir Iithology in this region is characterized mainly by the carbonate rock with the diverse reservoir types, large lithological change, varied fracture growth degrees and anisotropic distribution together with recent years of detailed exploration aimed at the low porosity and permeability reservoir, and thus the reservoir evaluation is difficult. There are mainly the following behaviors: :1) the reservoir Iithology is complex and the different Iithology is hard to identify with the conventional log.2) It is difficult for the log data to accurately calculate low permeability and low porosity in the reservoir with low porosity and poor permeabilty.3) with the multi reservoir types, the various reservoirs are difficult to differentiate , analyze the reservoir space texture and estimate the reservoir permeability using the conventional log. 4) the unsharpness of the log response traits in the high angle fractured reservoirs is difficult to recognize on the log presentation. 5) the anisotropic parameters of the reservoirs are hard to calculate with the complex reservoir space structure and dim log response traits. 6)as a result of the reservoir anisotropic impact, the reservoir fluid exerts less effect on the log curves so that the fluid property in the reservoirs difficult to estimate. 7) as the reservoir is obviously influenced by the structure, the structure azimuth and trend are not identified so exactly by the log information that it is difficult to estimate the growth orientation and fluid property horizontally.This paper places emphasis on the study and evaluation of reservoirs in Triassic Feixianguang Group Dias, Changxi group and Huanglong group. The method is established forFeixianguang Group Dias, Changxi group and Huanglong group. The method is established for modeling of the reservoir electrofacies and lithofacies by collecting the logging data of this block and normalizing the old logging data. The reservoir sorting and zonation standard are set up. The fracture identification and analytical procedure are investigated. The calculation method is determined for geological parameters relevant to the reservoir. The contrastive analysis is made for the reservoir fluid property estimation method. The effect is satisfactory.1 .Lithofacies model buildingAccording to the relationship between lithofacies and log responses, firstly, all sorts of lithofacies are defined using the petrographical knowledge and the multimineral model is utilized to analyze and calculate the mineral content; secondly the logging relational data base of mineral rock is established; finally the mathematical technique is adopted to make electrofacies analysis of the reservoir to obtain the consecutive geologic section.2. Multiparameter identification zonation and reservoir grade zonation standard The geologic and logging data show tha the reservoir sort in Jiannan region can be reduced to: pore-fracture, fracture-pore, fracture and pore. The grade stand...