Mason

You may have seen that my June 2006 Editorial contained a few errors, for which I apologize. However, I did find this process encouraging because, at the least, it meant that some people do spend a few minutes reading this editorial. Being corrected is a good and healthy part of learning, and to quote a Chinese proverb (seen on one of those business posters with a couple of swans at sunset), “Learning is like swimming upstream, as soon as you stop you are going backwards.” Learning is at the core of SPE Drilling & Completion. If you see errors or inconsistencies in any of our papers, please feel empowered to contact the authors (through the discussion forum in the online version of the SPE journals) and enhance the learning that you obtain from reading this publication. 

In addition to making mistakes, many of us unknowingly hold onto incorrect assumptions, but when an operational procedure runs into trouble or a piece of equipment breaks down, a valuable learning opportunity often arises.  For example, what happens when mud-pulse communication with a rotary-steerable assembly is lost? Does it maintain the existing build or drop rate or maintain tangent angle; can we make it continue our build or drop; will it walk? What happens when the nitrogen charge is lost in a gas lift unloading valve? Will it stay open or stay shut during unloading? In a subsea wellhead, what are the consequences of the 18¾-in. ring gasket failing to test? Would a resilient gasket be acceptable? Why not run resilient gaskets all the time?

A few months back, my company’s offshore production operations personnel reported that a downhole safety valve was proving very difficult to reopen after inflow testing; they said self-equalizing was taking at least 6 hours. Last week, with a well service supervisor offshore, it transpired that, because the transducer for remote monitoring of wellhead pressure was downstream of the wing valve, equalization was being attempted against a closed-production choke with the wing valve left open so that wellhead pressure could be monitored. When the wing valve was closed, and the local-pressure gauge on the tree was used to monitor wellhead pressure, the downhole safety valve equalized within 30 minutes. This reminded me of a concern that I have had for some time: Drilling and completion personnel deliver a U.S. $2-million, U.S. $20-million, or U.S. $100-million well carrying a future hydrocarbon-production value of U.S. $10 million, U.S. $100 million, or even U.S. $500 million; yet we just assume that production operations personnel know all about wells. We provide them with a two-page instruction manual that we grandly call a handover certificate—a manual that would not be acceptable to safely operate a U.S. $50 microwave oven.

Many of our business risks are in the interfaces between equipment, systems, and technical disciplines. Personnel who understand other disciplines and appreciate the significance of the interfaces will ask relevant questions to get others out of trouble. Still, there will be others who seem determined to take no interest in the well once “the plug is bumped.” It is all about an attitude to learning and a determination to move forward, not drift backward.  This edition’s papers, to help you move forward, are as follows.

Applications of Underbalanced-Drilling Reservoir Characterization for Water Shutoff in a Fractured Carbonate Reservoir—A Project Overview reviews a four-well carbonate underbalanced-drilling campaign, with well-design features to assist with water shutoff. Some areas of the world have treated underbalanced drilling as a bread-and-butter operation for many years, yet others are treading toward their first underbalanced well with great caution.

Top-Drive Casing-Running Process Improves Safety and Capability presents recent advances in casing running, showing how a casing string can be torqued, rotated, and washed to bottom by use of a top drive. Getting casing to bottom is often at the top of the list of risks for extended-reach drilling, with hook loads being too great to contemplate pulling a string that will not reach its planned depth. The system is new but proved, with a track record of more than 3 million ft of casing run.

A New OCTG Strength Equation for Collapse Under Combined Loads presents the theoretical development of improved equations for pipe collapse. Improved equations give greater reliability in the well-design process. Most readers will recognize the criticality of pipe-collapse predictions in many well-design and operational situations. 

Meeting the Challenges in Completion Liner Design and Execution for Two High-Rate Acid-Gas Injection Wells gives a case history of liner and cementing design for a high-alloy metallurgy liner subject to high mechanical stresses requiring acid-resistant cement.

Preventing Lost Circulation by Use of Lightweight Slurries With Reticular Systems: Depleted Reservoirs in Southern Mexico is a second case-history paper discussing cementing, but with a very different set of requirements in which fibers have been used successfully to control losses cementing in fractured carbonates.

Gravel-Pack-Placement Limits in Extended Horizontal Offshore Wells shows how understanding the wellbore hydraulics during high-rate circulating gravel packs allows the limits to be recognized and to be pushed further. This is clearly an important part in accessing more reserves for less cost and footprint—there is little point in drilling to the current limits of extended reach if completion practices are unable to keep pace.

Well Performance With Operating Limits Under Reservoir and Completion Uncertainties is an analysis of a large database of well-production performances showing which parameters dictate production rate and good business value. It is not often that such large databases are collated and analyzed.

Surface-Roughness Design Values for Modern Pipes provides an updated set of parameters for input to nodal-analysis well designs. Improving design inputs means better decisions, thereby specifying equipment for the right reasons.   

Monte Carlo Techniques Applied to Well Forecasting: Some Pitfalls discusses best practice in the use of Monte Carlo methods for determining well-construction duration estimates for well planning. Meaningful duration estimates lead directly to meaningful well-cost estimates, improving the business rigor and building the confidence that is needed to deliver “what we said we would do.” 

Happy reading,

John Mason