DN气田群位于库车坳陷东秋构造带东部，截止目前，该气田群已有DN1气田、DN2气田和DN3气藏，三级储量超过了2000亿m，而且还具有较大的增储潜力。DN2气田西部的成功评价和DN3气藏的发现，是变速成图技术在DN气田成功应用的结果。围绕DN2气田评价及DN3号构造落实过程中使用的变速成图方法进行了论述，指出DN气田群构造落实的关键是速度，在三维覆盖区叠前深度偏移技术是落实圈闭最有效的方法，在二维区，层速度充填法最有效。

DN gas fields are located in the Dongqiulitage structure belt in Kuqa depression. Currently, three gas reservoirs, DN1, DN2 and DN3, have been discovered with 3P reserves of more than 2 000×10⁸m ³ in the reservoirs. More gas are expected to be discovered. With the successful application of varying velocity mapping technology, we have estimated the DN2 gas field and discovered the DN3 gas reservoir. Interval velocity is the key factor in discovering traps. This paper discusses the method about varying velocity mapping used in estimating the DN2 gas field and discovering the DN3 gas reservoir. The good method to discover or estimate traps is that the prestack depth migration technology is used in 3D work area and the interval velocity filling is used in 2D work area.