An Analytical Model for Predicting Composite Inflow Performance Relationship for Fishbone Drilling Technology with N Number of Ribholes

Summary Fishbone drilling has gained significant attention globally, with numerous applications and successes in many oil and gas fields. This technology offers a more environmentally friendly alternative to fracturing, reducing induced seismic activities in critically stressed regions. In addition, fishbone wells increase production, connect natural fractures, and bypass damaged zones. However, despite its benefits, few models accurately predict production rates from fishbone wells, hindering informed technical and economic decisions. Existing models are often complex and difficult to apply, especially in new fields lacking historical production data. With this study, we present a simplified mathematical model, building on previous work from the literature; ribholes are assumed to be a conduit inclined at an angle θ to the horizontal in the development of the model. The analytical model combines flow in the matrix with the flow in the ribhole considering pressure drop due to friction and accumulation along the ribhole sections. The governing equations and the solution procedures are included in the work to enable readers to reproduce all results. The model was validated by applying it to the multilateral stimulation technology (MST) in the Austin Chalk carbonate reservoir in Texas, USA. A reasonable agreement was observed between the field measurement and a commercial numerical simulator (CMG, Computer Modelling Group, Calgary, Alberta, Canada). The present model outperforms previous models, showing superior accuracy with a minimal prediction error. The excellent result of the new model is attributed to the included pressure drop terms in its development that were initially ignored by previous authors. The sensitivity analysis of the present model shows that the angle of inclination and the number and size of the ribholes are the major variables that influence the performance of fishbone wells, while the length of the ribholes has the least effect on production. Finally, the present model will ensure that both technical and economic decisions are taken within the shortest time period. This model can be extended for predicting production from fishbone drilling in geothermal reservoirs.