THE DISCOVERY OF OIL AND THE CHARACRISTIC OF GEOCHEMISTRY ON THE PERIPHERY OF SONGLIAO BASIN

1 The discovery of oil in Xiushui basin

Xiushui basin is Jurassic basin which develops above the base of Haixi fold and Precambrian on the south periphery of Songliao basin（the most important oil and gas production areas in China）. Xiu D1 geology survey well finished in 2016 is the first one to reach to Mesozoic group in this area. Much oil and gas shows are discovered in Haifanggou formation. The thick of Oil show at oil spot and oil stains level reach to 240.68, and at oil immersed level reach to 17.56m.

2 The geochemistry charateristic of hydrocarbon

There are 51 hydrocarbon samples and 12 oil sand sample analyzed from Xiu D1 well.

2.1 The base characteristic of hydrocarbon

For the whole well, the content of organic coal (TOC) in hydrocarbon is at 0.28%-2.8%, the average is at 1.15%; the hydrocarbon generation potential (S₁+S₂) is at 0.13mg/g-9.44mg/g, the average is at 2.18mg/g, mainly concentrate on the range of inferior-middle level hydrocarbon. The type of organic material is type Ⅱ. The mature of organic material (Ro) is at 0.83-0.97, which is at the stage of mature

2.2 Characteristic of hydrocarbon and oil biomarker composition

Saturated hydrocarbon is the most in the hydrocarbon, and the second is arene, the hydrocarbon contain less non-hydrocarbon and shows asphaltene. The characteristic of isoprenoid prove that weak-reduction and light oxidation atmosphere. The Gamma indexes of all samples are all below 0.16; this shows that the salinity of water was low in the period of sedimentation. The characteristic of sterane explain that higher plant from terrestrial is dominant contribution accomplished by aquatic organism.

3 Conclusion

3.1 The estimation of hydrocarbon

Each index of organic material shows that hydrocarbon of Xiu D1 are at inferior-middle level, hydrocarbon at depth from 400m-550m are at middle-superior level; the type of organic material is Ⅱ, dominated by Ⅱ₁. Hydrocarbon below 650m is at the stage of maturity to high maturity. Therefore, hydrocarbon at depth from 650m to 830m is predominance oil generation strata.

3.2 The analysis of oil-source correlation

The biomarker characteristic of hydrocarbon and oil shows that the hydrocarbon of Xiu D1 has genetic relationship with oil, so the oil is self storage and self storage type.