Inflow Performance Relationships for Solution-Gas-Drive Slanted/Horizontal Wells

Abstract

Abstract Since 1968, the Vogel equation has been used extensively and successfully for analyzing the inflow performance relationship (IPR) of flowing oil wells under solution-gas drive. Oil well productivity can be rapidly estimated by using the Vogel IPR curve and well outflow performance. However, the Vogel curve was originally developed for conventional vertical wells and may not be valid for slanted and horizontal wells. The development of IPR’s for slanted and horizontal wells by using a vertical/horizontal/slanted well reservoir simulator is presented. Several important results were observed. First, the IPR’s for slanted and horizontal wells are similar to the parabolic behavior of the Vogel IPR curve. Second, IPR data generated for slanted wells by using the Vogel curve can differ as much as 22% from that of the new IPR data and 27% for horizontal wells. Third, the right curvature shift of the Vogel curve for slanted and horizontal wells indicates that these wells are more efficient producers than vertical wells from a subsurface fluid flow viewpoint. Fourth, a minimum slant angle of 45 degrees is required to increase oil productivity by 50% over that of a vertical well. A slant angle of 60 degrees or greater can increase oil productivity more than two times that of a vertical well. The newly developed IPR data are compared with existing empirical and field data. Several application examples are presented to illustrate the use of these IPR’s to predict slanted/horizontal well productivity.