Drilling Optimization in the Low-Resistive, Thin-Layer Reservoirs of Northern Oman

Abstract

Ultralow-resistivity reservoirs, common in Oman, are frequently encountered when drilling wells at the flank of an infill field with nearby oil/water contacts (OWC) in a reservoir sweet spot window of 1 to 2- m true stratigraphycal thickness (TST). An integrated solution developed to better position the wells in this type of reservoir has resulted in successful cases on net-to-gross (NTG), which exceeded expectations in terms of wells production and well deliveries. Integrating resistivity propagation curves response with directional resistivity curves (distance- to- boundary curves) response allows for optimizing well placement and assists in determining the best approach of well objective during drilling. Once drilling the lateral section began, a careful evaluation of the distance-to-boundary service tool inversion and directional measurements were performed in addition to conventional resistivity curves evaluation. This procedure ensured accurate placement of the well; thereby, avoiding water contact. Drilling optimization in long lateral sections has been carried out by optimizing bottom hole assembly (BHA) design, bit selection, and drilling parameters, taking geo-mechanics and geological uncertainty factors into consideration.