Optimizing Lateral Lengths in Horizontal Wells for a Heterogeneous Shale Play

Abstract

A successful evaluation and development program in oil-and gas-bearing shales requires considerable analysis and investment, not to mention optimization to help ensure a profitable outcome. Accelerating optimization, reducing capital expenditures, and improving lifecycle net present value (NPV) for the asset are reasonable goals. Seven shale properties are key drivers to help achieve successful play economics. However, the heterogeneity of shales makes well location selection difficult without appraisal well logs and geostatistical mapping of shale property quality. The analysis method allows operators to quickly high-grade areas within a large, heterogeneous shale play using logging suites from a limited number of wellbores in the play. Further, the methodology has been extended to quantify the play's potential reward versus risk distribution for in-fill drilling investments. This study extends the method to optimizing lateral lengths of horizontal wells. Geostatistics provides a means to determine correlation lengths of aggregate shale properties known to be critical to successful economics. The correlation length is used to determine the appropriate length of the horizontal well lateral, restricting it within the highest rock quality for stimulation effectiveness and production rates. Because optimal lateral lengths can be predicted using this approach, it is now possible to pinpoint the best wellhead location, the best landing point for the horizontal portion of the well, and set the optimal length of the lateral. This reduces the drilling of unproductive lateral lengths and targets stimulations. By shortening the "trial-and-error" evaluation lifecycle stage using this methodology, an operator can develop an asset more quickly and at less cost than with previous approaches.

Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

“…In detail, the production per shale gas well correlates positively with the length of its lateral (e.g. Chorn et al 2014); the present calculations are readily scalable for any 5 length of lateral or production figure per well. The aforementioned estimate for seasonal heat storage of ~6 TJ or ~2 GWh, derived for a 2000 m long lateral, can likewise be scaled to any other length of lateral and summed over whatever number of laterals of a given length is required to achieve a given shale gas production target.…”