关键词: 鄂尔多斯盆地, 上古生界, 低压气藏, 压力梯度, 地层温度, 埋藏深度

Abstract: The fluid pressure is obviously lower than the static pressure in gas reservoir of the Upper Paleozoic in Ordos Basin. The fluid pressure gradient of the reservoir is high in the east part and low in the west part. Its change is accordant with the current structural gradient. It is suggested that the low pressure gradient of gas reservoir in the Upper Paleozoic was resulted from the increase in depth of the later sedimentation and the decrease of temperature during erosion. The fluid pressure gradient of Sulig Gas Field was 1.22 MPa per a hundred meters of formation, when the temperature of reservoir formation was 150℃. The pressure gradient decreased about 14.9 percent with temperature decreasing during erosion. The pressure gradient was about 1.06 MPa per a hundred meters of formation at the end of the Cretaceous and decreased about 21.4 percent with the depth increasing in the Cenozoic. Thus, the representative low-pressure gas reservoir could be formed in Sulig Gas Field.

Key words: Ordos Basin, Upper Paleozoic, low-pressure gas reservoir, pressure gradient, formation temperature, burial depth