Drilling advances

June 1 signaled the start of the dreaded Atlantic hurricane season and with it, the likelihood of waiting-on-weather missives cropping up regularly on daily Gulf of Mexico (GOM) drilling reports. While we can only hope that meteorologists are somewhat on target with their 2014 forecasts of relatively calm climatic conditions offshore, it’s been anything but that onshore.

Indeed, an unseasonably bitter winter, by U.S. standards, was followed by a deadly rash of tornadoes that slammed across many E&P theaters in the South and Midwest. As for the winter, the Arctic-like conditions that kept much of the country in a deep freeze were a double-edged sword, in that they generated an appreciable spike in natural gas prices, but at the same time prevented rig and frac crews from doing their jobs. As one who had the “opportunity” to visit some drilling locations in Nizhnevartovsk, Western Siberia, in the dead of winter, the notion of working on a rig floor under those conditions runs contrary to my more tropically inclined sensibilities.

While operators in perennially windswept North Dakota are accustomed to brutal winters, they say nothing compared to the one just passed. Although production in the Bakken-Three Forks shale rebounded impressively, to notch up a daily record in March, output was flat in January following an unprecedented decline of 53,226 bopd in December, reportedly the largest drop since the state began keeping records.

In what the state’s chief regulator described as “one Arctic clipper after another,” a significant portion of North Dakota experienced its third coldest December ever, with the abnormally harsh conditions continuing into the early part of this year. Reports had the numbing cold freezing diesel in tanks, while most of January also saw winds peaking above 35 mph, putting a further damper on drilling and fracing operations. “The biggest production impact was still the weather,” Lynn Helms, director of the North Dakota Industrial Commission Department of Mineral Resources (DMR), told Reuters. “February had 18 days with temperatures five-plus degrees (Fahrenheit) below normal. Add to that, four days with wind gusts too high for completion work, and progress is slow.”

Remarkably, aggregate production still managed to hit the one-billion-bbl landmark this year, but producers said it could have been significantly higher and achieved sooner, had the weather cooperated. Onshore operators had no more thawed out, and returned to business as usual, when a string of deadly tornadoes roared across much of the U.S. petroleum sector between April 27 and 30.

The hardest-hit area was Arkansas’ Fayetteville shale, where Southwestern Energy Co. (SWN) is a major player. While the independent says its wellsites made it through relatively unscathed, many of its employees were not so lucky. “Several in the SWN family have experienced great loss, including homes destroyed and loved ones lost,” CEO Steve Mueller said during the first-quarter earnings call. “We’re heavily involved in supporting this area with resources for the Greater Arkansas American Red Cross, to aid in their relief efforts there.”

Calm waters ahead? Getting back to the offshore, on May 22, the National Oceanic and Atmospheric Administration (NOAA) released its annual forecast, where it predicts near-to-slightly-below historical activity levels, with up to an expected high of 13 named storms, defined as packing sustained winds of 39 mph or higher. But, in the words of Caribbean crooner Jimmy Buffet, “there ain’t no reasonin’ with the hurricane season,” so the inexact science that is hurricane forecasting is largely dismissed by drillers, who continue to prepare for the worst.

Prior to release of the NOAA prediction, private forecasters ImpactWeather and AccuWeather concurred during a one-day industry symposium in Houston that all indications point to a relatively mild five-month hurricane season. Nevertheless, Chris Hebert, ImpactWeather’s chief hurricane forecaster, admitted to the Houston Chronicle that forecasts mean little to offshore operators. “For the most part, for the private industry, the forecast is a curiosity. There’s nothing different they do.”

No less than seven papers dealing with ocean storms, and the loop and eddy currents that put many a GOM floater in time-out, were presented at last month’s Offshore Technology Conference (OTC) in Houston. While most of the papers dealt with meteorological modeling and measurements, others focused on operational issues. One such paper, co-authored by Stress Engineering Services and the Japan Agency for Marine-Earth Science and Technology, focused on lessons learned from a 2012–2013 deepwater drilling campaign in the Nankai Trough off Japan.

 The program was conducted from the Chikyu drillship in 6,361 ft of water, with surface currents exceeding 3.5 knots. The authors detailed the operational issues evaluated, including riser deployment and retrieval; the landing approach for the BOP and lower marine riser package (LMRP) with the vessel drifting; typhoon evacuation plans; hang-off operational criteria; allowable riser tension range; and riser fatigue measurement with vortex-induced vibration (VIV) monitoring. The paper featured general guidelines and associated criteria for evaluating a drilling riser system under various inclement conditions.

Stress Engineering and Shell also presented a methodology for monitoring riser and subsea wellhead fatigue, under the abnormally high surface and subsurface currents intrinsic of the deepwater GOM. The semi-analytical approach for estimating wellhead fatigue, by examining BOP stack motion data, also touched on considerations for vibration mitigation. The methodology was developed during a GOM drilling program in up to 7,000 ft of water, with surface and subsurface currents as high as 5.0 and 1.5 knots, respectively.