Production Data Analysis and Practical Applications in the Sulige Tight Gas Reservoir, Ordos Basin, China

Table 1

Common problems in the production data diagnosis of the tight sandstone gas reservoir.

	Problem	Cause
I Unsteady state	① Flat early data	Contaminated well
	② High early data	Initial reservoir pressure is low
	③ Normalized rate increases with time	Well washing
	④ Step-shaped early data	Initial reservoir pressure is high? Large tubing size
II Transitional stage	⑤ Early arrival of boundary flow	Bottom hole overstock liquid
III Pseudo-steady state	⑥ Data below the 45-degree slope line	Bottom hole overstock liquid
		Pressure loss caused by wellbore instability
		Multiwell interference (Energy leakage)
	⑦ Not unified	Unstable production (Workover, etc.)