To the casual observer of completions and hydraulic fracturing, it might appear that multifractured horizontal wells are a relatively recent concept that materialized just as we required them for unconventionals. However, those in the know will recognize that the marriage of fracturing and stimulation operations with horizontals was forged almost 30 years ago in an environment far removed from unconventionals.
In fact, it was the high-cost, limited-well, offshore environment that drove the need for higher production rates from single wellbores and indeed from horizontals and high-angle wells because of the limitations imposed by platform footprint and achievable step-out geometry. Substantial progress in multifractured horizontal wells was made in the 1990s by operators such as Maersk on the Dan field and BP on the Valhall field, in addition to onshore experiences with various operators such as UPRC in the Austin chalk and Arco in Alaska (the North Slope operational reality being effectively similar to offshore). Therefore, it is with great satisfaction that this month’s technical section includes papers demonstrating technologies from unconventionals that are beginning to be used to develop these offshore opportunities further.
This month’s selections highlight a number of such applications, including open hole and cased hole, ball-drop actuated, and proppant plug staging. Most of the tools and approaches developed (onshore) for high efficiency in low-permeability propped fracturing are not currently wholly applicable to higher-permeability (offshore) environments because they typically depend on overdisplacement by design. However, these technologies are a fast-moving target, with highly cost- and time-efficient coiled-tubing (CT) underdisplacement techniques emerging now across unconventional plays. This means that we should see articles here very soon on these CT-deployed propped-fracturing approaches as they move offshore.
As these innovations gain widespread acceptance, I would expect that the application of offshore fracturing will become a more attractive proposition once again. However, in all cases, the most critical aspects to achieving success will be that the technologies selected not only be fit-for-purpose but also reflect the formation quality and completion philosophy, rather than trying to fit square pegs into round holes.
Recommended Additional Reading
SPE 170773 Flushing Away the Profit: The Potential Misapplication of Unconventional Fracturing Technology on a Global Scale by M. Rylance, BP, et al.
OTC 24179 Drilling and Completing Cascade and Chinook Wells: A Design and Execution Case History by Flavio Dias De Moraes, Petrobras, et al.
OTC 25321 Ultrahigh-Strength Proppant Developed for Deep, Offshore Completions by Terry Palisch, Carbo Ceramics, et al.
Martin Rylance, SPE, is senior adviser within the BP Global Wells Organization. He has worked with BP and its partners for more than 28 years. Rylance holds a BS degree in pure mathematics. He has been involved in all aspects of pumping operations, well control, well intervention, and pressure service. More recently, Rylance has specialized in unconventional-resource development and hydraulic fracturing in tectonic regimes and high-pressure/high-temperature environments. He was an SPE Distinguished Lecturer in 2006–07 and again in 2013–14 and serves on the JPT Editorial Committee.
