Research On The Logging Evaluation Technology Of Low Resistivity Reservoir In Area A Of Jiyuan Oilfield

Ordos Basin is the second largest sedimentary basin in China, which is also one of the first discovery, exploration and development large-scale petroleum-bearing basins. In recent years, many low resistivity reservoirs are found in the basin, as oil and gas exploration and development work is continued to deepen. In general, the low resistivity reservoir means that the ratio of oil and water of resistivity is less than 2 in the same water system. Area A of Jiyuan Oilfield is in the eastern part of Jiyuan zone, in which the reservoir is mainly low porosity, low permeability and low oil saturation in the Mesozoic, so that the impact factor from the oil and gas on log response is small to lead to Rt/R0<2.0, while showing a typical low resistance characteristics, so the ability Distinguishing for oil and gas under log information is greatly reduced.In this paper, the information of the Chang 2 reservoir is to target. Through acquiring the low resistivity reservoirs in the latest research at home and abroad, collecting the dynamic and static information in the area, observing and analyzing the data from the core, we start to analysis reservoir geological features making full use of low resistivity reservoir logging curve. While the studies on construction and sedimentary microfacies suggest that it is low structure rate, as the lithologic-structural reservoir, and it has three microfacies developed including underwater distributary channel, underwater natural levee and underwater distributary interchannel; the studies on the reservoir properties and well log characteristics illustrates that rock particles is smaller, physical properties are relatively poor and oil is not a traditional "low-aggression," while showing "high invasion" feature; The studies on the low resistivity reservoir determination of fluid and mineral composition, structural characteristics of reservoir decide the causes of the low resistance genetic mechanism; The "four characteristic relations" studies and the parameter models for resistivity reservoir will be established; Based on the "four characteristic relations" results and the consideration of the causes of low resistivity reservoirs in the area, we make use of conventional logging curve, propose for the seven kinds of qualitative identification, and establish the low resistivity reservoirs criteria for distinguishing combining with effects of data for testing. Finally, based on the characteristics in the area, the methods of seven kinds of qualitative identification of low resistivity reservoirs and the Identification standards are used to comprehensive interpret the remaining wells and more than 80% of which can be identified. By this way, the favorable areas for further exploration can be indicated and the identification and evaluation results for the complex reservoir are improved.