Evaluation of prosper for modeling long lateral gas well productivity in toe up, toe down, horizontal well geometry.

摘要

Most horizontal wells are not truly horizontal and may be drilled `toe-up' or `toe-down' to follow geological formations or in an attempt to keep the well from loading up. Challenges in directional drilling may also lead to horizontal gas wells with undulating wellbore profiles. This wellbore profile creates natural traps for heavy fluids in the lows and light fluid in the highs, which may result in chocked production. Hence, there is an interest in determining the best wellbore trajectory -- toe-up, horizontal, or toe-down -- for well unloading.;This study evaluates the capability of the well productivity software PROSPER to model potential liquid loading as a function of toe-up, toe-down or horizontal well geometry, using data for two wells located in a tight gas reservoir in Arkansas. The wells used in this study have different geometry but were drilled from the same pad. Using the well trajectory data and fluid PVT properties, a fractured well model is constructed and matched to the well's production. Once the match is achieved, the lateral is inclined (toe-up) and declined (toe-down) at 5 degree intervals. A parametric study is performed using two different water gas ratios for each inclination angle. The fluid gradient along the length of each lateral, including flow regime, slip velocity, and holdup are tabulated, and the likelihood of liquid loading is noted by applying general screening criteria.;Results from this work illustrate a slight advantage for the toe-up configuration based on the screening criteria applied. However, it should be emphasized that standard well productivity software is limited in modeling this problem. Those limitations are identified in the work.