Abstract: Exploitation of reservoirs can use either vertical wells or horizontal wells. Wells can be either fractured or unfractured. In well stimulation selection of field practice,the stimulation proficiency is usually taken into account at first besides of stimulation cost. The stimulation proficiencies of vertical wells and horizontal wells were studied under two circumstances of wells being fractured and not fractured. The effects of pay thickness,drainage area,fracture number,rock permeability and fluid viscosity to stimulation proficiency were also studied separately. The study shows that the stimulation proficiency of unfractured horizontal wells is not so good as vertical fractured wells. The thick oil layer is suitable for being exploited by vertical wells,while the thin oil layer is more suitable for using horizontal wells than vertical wells. The larger drainage area of wells cannot increase their stimulation proficiency largely,and can prolong the production time of wells. The fracture number of wells can increase their stimulation proficiency very effectively. The volumetric fracturing or multi-stage fracturing is the most effective stimulation method of horizontal wells. Horizontal wells cannot demonstrate higher stimulation proficiency without fracturing. The middle and high permeability reservoirs can take any types of well for exploitation,but the low permeability reservoirs must use fractured horizontal wells. The middle and low viscosity oil reservoirs can take any types of well for exploitation,but the high viscosity or heavy oil reservoirs must be developed by the aid of thermal recovery method.