Improved drilling technology, low-permeability reservoirs, and pockets of reserves too small to support the economics of drilling a well are increasingly compelling operators to turn to high-angle and extended-reach wells. However, the geometry of these wells and their often thin economic margins may cause operators to forgo obtaining certain types of while-drilling or wireline logging data, particularly data used to plan effective stimulation programs. Without these logs, operators have typically distributed fracture stimulation treatments evenly along high-angle well pay zones rather than at specific measured depths. Results have shown this approach to be inefficient, with production coming from only some of the treated intervals.
To meet these challenges, an innovative logging technique was designed to use small-diameter logging tools and a specialized bit to obtain openhole logs across entire high-angle and horizontal intervals. The logging tools are run inside the drillpipe and into the open hole through a hole in the face of the bit. Operators are thus able to obtain a full suite of gamma ray, resistivity, neutron, density, and sonic measurements, enabling them to optimize fracture spacing on each well.
An article in the Summer 2012 issue of Oilfield Review describes how this through-bit logging technique has significantly improved returns on stimulation investments in high-angle wells. Case studies from North America demonstrate how operators now design fracture programs using data that were unavailable to them in earlier offset wells. One operator was able to reduce completion costs per stage by about 60% while increasing the number of stages per lateral section. Furthermore, based on 30-day production averages, oil production from the wells logged through the bit was double that of earlier wells treated without benefit of the technique.
Read the full article by visiting the Oilfield Review Web site.
Aivalis J, Meszaros T, Porter R, Reischman R, Ridley R, Wells P, Crouch BW, Reid TL and Simpson GA: “Logging Through the Bit,” Oilfield Review 24, no. 2 (Summer 2012): 44–53.