Overview: Well Intervention and Control (January 2008)
Authors: Barnett David 
Published: February 2015

Overview
In the last 25 years, we have witnessed the introduction of technology that is nothing short of astonishing—things that most of us would never have imagined during our early days in the field and on the rigs. While the biggest effect clearly has been on overall drilling efficiency—especially real-time information while drilling—it is interesting to look at how technology has affected the well-control aspect of drilling.
Today, we have the ability to look at a computer screen that provides a virtually instantaneous reading of numerous downhole parameters (e.g., annular pressure near the bit, equivalent circulating density, temperature, torque, vibration, and lithology). Advances in surface monitoring have lead to significant improvements in computerized displays of pressures, rates, and volumes, all of which are crucial to maintaining hydrostatic control of the well.
Some may wonder how wells were ever drilled without these high-tech tools. In December 1982, there were 4,530 rigs running in the US vs. approximately 1,800 rigs running in the US today. When those 4,530 rigs were drilling back in 1982, measurement while drilling (MWD) was in its infancy—Schlumberger did not complete their first commercial MWD project until some time in 1980. That means that there were more than 4,500 rigs drilling away, mostly without the benefit of any real-time bottomhole information except for what could be derived from experience-based surface observations.
Anyone remember what a computer looked like in 1982? That was the year Intel introduced its 80286 processor with a blazing 6-MHz speed—the computer used to produce this article runs 6,000 times faster. Obviously, there were no computer screens in the drilling supervisor's office giving 24-hour graphical and numerical readouts in real time. If there was a computer on site, it was probably busy with a game of pong, or maybe a basic spreadsheet.
Technology has allowed our industry to advance to a point where pressure is manipulated for the purposes of increasing drilling efficiency and reducing formation damage. It used to be that any kind of pressure at the surface was a sure sign of a problem. Primary, well control inherently meant the absence of surface pressure. Now we have underbalanced drilling and managed-pressure drilling that seem completely foreign to this long-held concept.
Numerous articles could be (and probably have been) written about the risk/reward aspects of where technology has allowed us to venture. Sometimes it is just interesting to sit back and look at where we were not that long ago. You cannot help but wonder where continued advancements will lead over the next 25 years.
Well Intervention and Control additional reading available at the SPE eLibrary: www.spe.org
SPE 107234 "First Subrigfloor HWO Intervention System for a Floating Vessel" by Tim Pollock, BP plc, et al.
SPE 108408 "Fishing 10,000 ft of CT From a Deep Gas Well in Saudi Arabia" by Hasan H. Al Jubran, Saudi Aramco
Available at the OTC Library: www.otcnet.org
OTC 18614 "Using BOPs at Pressures in Excess of the Rated Working Pressure—A Solution for High-Pressure Wells?" by M.E. Montgomery, SPE, WEST Engineering Services, et al.