CHARACTERISTICS OF THE EVOLUTION OF THE CRUDE OIL FROM QINGLONG GROUP OF JURONG DEPRESSION IN SOUTHERN JIANGSU AND THESTRATEGY FOR OIL FINDING

The Mesozoic Jurong depression is located in the Western part of Southern Jiangsu, with an area of about 1325 km².Twenty-five wells were drilled on the Jurong anticline in the middle part of the depression (including 4 eoal-field exploration wells). The production of the initial test of Rong No.2 Well in lower Qinglong group (T₁) limestone was 6.6 m³/day of oil, while the highest production of Rong No.3 Well was 10.1 m³/day. Owing to the lack of formation energy, and the poor physical properties of the reservoir, the production decreased rapidly and finally dried up. The analysis of crude oil and the quality of coal indicate that this is a low mature heavy oil and lignite area. According to the graph of fixed carbon ratio distribution, middle or small pools may be found at the flanks of the depression where the degree of evolution is higher.