Research On Characteristics Of Natural Gas Reservoiring In Hangjinqi Of The Northern Ordos Basin

Hangjinqi region is located at the north of the Ordos Basin, whichacross two tectonic belt of Yishan slope and Yimeng uplift. As the UpperPaleozoic reservoir is dense、the pressure is abnormally low and everywell produces water, and the relationship between oil and water iscomplicated, which restricted the further exploration. In connection withthe problems we study thoroughly about the pressure causes、 therelationship between oil and water and its main controlling factors, thenwe achieved the following understanding:（1） The Hangjinqi region’s pressure is abnormally low, thecoeffient in the plane on the overall is south high and north low.Theabnormally low pressure’s main reason of is gas loss,Uplift cooling hasa certain role in the forming of abnormal low pressure;（2）Accroding to the analysis of the study area’s sand distribution、water distribution and the dominant channel of hydrocarbon migration and so on. Wefound the south of Hangjinqi region’s structure is not developed, and He1and Shan1’ssand has large thickness and has good connectivity conditions and itslithology control gas and water distribution, hydrocarbon accumulation in He2throughthe change of lithology and the local cracks. In the north of the fault zone the localstructures help the accumulation;（3）Hangjinqi region mainly rely on the situ gas source. But in the north ofHangjinqi region the natural gas lateral migrated through the southern district, andvertical migrated through the different levels of faults, then redistributed to the localstructural traps from gas pool, and its gas-bearing bits gradually increased from southto north； （4）Accroding to the study of excess pressure and mudstone thickness andadvantages of transporting sand and faults and unconformities, we found thatHangjinqi region’s regional seal is the upper Shihezi formation Shiqianfengformation’s silty mudstone and mudstone, which is wide distributed and effectivelyclosed the fluid upward movement, the pressure of the regional seal closed and matterclosed controls the gas-bearing bits, the Upper Shihezi and above layer can producegas only close to the fault or unconformity near, ultimately, in the Wulangeer raisedthe formation of Cretaceous oil seeps;（5）The model of the southern fault of Hangjinqi region is low abundancelithologic proximal accumulation, and the favorable reservoirs were He1and Shanxiformations., the favorable area is the east of Jin7, at the same time we need to take fullaccount of the thermal maturity of source rocks. The north of fault is distant sourceof construction and lithology accumulation, the favorable reservoir was lower Shiheziformation, the favorable area was Shiguhao area.