A successful hydraulic fracture treatment was performed on a delineation well in the Lisburne naturally fractured reservoir, North Slope, Alaska during extremely severe weather conditions. The well performance information from this delineation well was of critical importance to the development and subsequent funding of the ﹩2 billion Lisburne project. Logistical problems which developed prior to the fracture treatment required special design considerations usually taken for granted in many North American locations. Special considerations for economy, the environment and safety were integrated into a straightforward hydraulic fracture treatment performed at a wind chill temperature of -85F (-51F ambient).
This paper discusses the fracture design and February 11, 1984 field treatment which led to the successful stimulation of the South Bay State No. 1 delineation well. Also included is a discussion of the results obtained from the subzero hydraulic fracture treatment. A better understanding of equipment performance, fluid rheology, proppant mixing, logistic limitations performance, fluid rheology, proppant mixing, logistic limitations and human elements under severe weather conditions was gained from the treatment.
In addition, this paper addresses the following cold weather concerns that arose prior to the implementation of the fracture treatment:
o Use available equipment, successfully perform hydraulic fracture treatment.
o Mix proppants and additives "on the fly".
o Proper function of electronic, pneumatic and hydraulic systems as well as rubber conveyor belts.
o Safe and proper seal of surface tubulars.
o Rheological properties of gelled diesel.
o Effects of the elements on human beings.
o Pre-frac breakdown to gain more data.
o Uncomplicated pump schedule.
Oil development on Alaska's North Slope has emerged as one of the most prolific undertakings in recent history for the domestic petroleum industry. Figure 1 shows the Arctic Slope region located petroleum industry. Figure 1 shows the Arctic Slope region located north of the Brooks Range approximately 600 miles north of Anchorage, Alaska. Over 60 billion barrels of oil have been discovered on the North Slope since the late 1960's and development of these reserves continues even today. Drilling and production operations in this area encounter many unique problems. production operations in this area encounter many unique problems. Hostile weather, a fragile environment, darkness and remoteness all contribute to difficult and expensive North Slope operations.
Temperatures in southerly locations may be as low as those in Alaska, but persistence of Arctic cold, combined with other factors such as wind, remoteness, long spells of darkness and poor visibility, severly impact the efficiency of North Slope oil field operations. Figure 2 shows the Prudhoe Bay average monthly temperature variations for the last five years. It is interesting to note that the wind chill temperature rarely dips below -70F during this period, however, during February, 1984, record cold temperatures were recorded on Alaska's North Slope.
Many nonessential well operations and maintenance projects within the Prudhoe Bay Unit shut down when temperatures fall below -30F ambient. The subject hydraulic fracture treatment was performed at -51F ambient because no relief from the cold weather was predicted for several weeks and the low productivity from this key delineation well could have impacted funding of the Lisburne project. project. P. 209