Abstract: Taking sandbodies in the second member of Guantao Fm in Cao 20 block of Le'an oilfield as the study object, distribution pattern of remaining oil in late huff and puff stage and the feasibility of well pattern thickening are studied through numerical simulation, development geology and performance evaluation and dynamic monitoring. In the late huff and puff stage of the sandbodies in the second member of Guantao Fm, heating radius is 50m, the rate of producing reserves is low in plane, the amount of interwell remaining oil is relatively large, and the potential of development adjustment is high. The current well spacing and well pattern in the sandbodies in the second member of Guantao Fm have the material base for infilling adjustment and oil recovery factor can be enhanced over 5% through well pattern thickening. Based on these study results, the well pattern of the sandbodies in the second member of Guantao Fm in Cao 20 block is thickened and the development effects are improved.