By Joanne Liou, associate editor
Growing activity in the Gulf of Mexico (GOM) reflects the industry’s capability to meet increasing operational challenges in deepwater, where activity has returned to pre-moratorium levels despite more stringent regulations. Schlumberger, which relocated resources to other basins during the moratorium period, has moved resources back to the GOM as activity returned and is continuing focus on geological and reservoir challenges that lead to narrow operating environments.
“That is a challenge for the GOM, and some potential shallow hazards, such as shallow water flow or near-surface faults, add more complexity to the operation. As you access the reservoir, drilling through the salt, compounded by uncertainty on the pore and frac gradients and very narrow operation mud weight window, adds challenges during the drilling process,” Wallace Pescarini, vice president, deepwater operations, said.
To address such challenges, Schlumberger is combining real-time drilling evaluation data with the reservoir model using advanced interpretation techniques to analyze and act on the data in real time. Seismic-guided drilling is one example, in which the LWD checkshot data are used to constrain the surface seismic model in real time to help narrow down the depth uncertainty and to identify overpressure zones in front of the drill bit, Mr Pescarini said.
In the GOM, petrophysical and seismic data from offset wells are used to create a model of the formation pressures. “By leveraging the latest advances in computing power, we are now able to re-migrate the seismic model around the well while drilling,” he stated. “This allows us to predict the formation pressure up to 1,500 ft (457 meters) in front of the drill bit.” The drilling program can then be modified to reflect the real-time predictions.
Another trend that continues to evolve, mainly to respond to the described operational complexity, is the capability to bring drilling experts together as an integrated team during the planning and execution phases, supported by real-time workflows. “This is a trend you are seeing in the market. Specifically in the GOM, we are very well supplied with these experts and have located them in our PetroTechnical Engineering Centers to ensure that a collaborative environment is created.”
The ultimate aim is to drill fewer wells but produce more oil. “To be successful, every well has to be in the right place and be able to produce over the entire life of the field,” Andy Hawthorn, Schlumberger business development manager, earth model building, said during a presentation at the company’s re-launch of its Digital Technology Theater in Houston in March. “Industry statistics show that with GOM wells in over 3,000-ft water depth, about 45% to 48% of all wells require a sidetrack. Of those, 50% require more than one sidetrack, which means we’re not getting it right the first time, all the time.”
Close collaboration among operators, contractors and service providers will be key going forward, as downhole nonproductive time (NPT) continues to increase, driven by the increasing geological complexity of deepwater E&P. “There is a four-fold increase in NPT due to wellbore instability and mechanical instability,” Mr Hawthorn said. “There is also a four-fold increase in the number of times BOPs are activated as the complexity of wells increases.”
Reducing NPT will require a combination of efficiencies within the drilling operation, coupled with putting wells in the right place the first time so it can produce over the entire life of the field. “You have to combine softwares and combine disciplines and expertise. You have to understand how much uncertainty you have in your measurement and the assumptions you made in your workflows before you hand it to the next set of people to do the next sequence of processing.”
For a project in the subsalt Wilcox structure in the GOM, Schlumberger generated 1,000 models of what the top Wilcox would look like. “This is the starting point because attempting to quantify on the amount of uncertainty allows you to make the correct measurements that drive the uncertainty down, allowing you to make objective decisions,” Mr Hawthorn explained. A simple one-dimensional stretch in most cases is no longer adequate. “We are dealing with a 3D, and increasingly, 4D environments. This requires a better approach.”
Digital Technology Theater
The Digital Technology Theater (DTT) in Houston is a key platform Schlumberger is using to help operators in the Gulf of Mexico. A re-launch event in March focused on showcasing the company’s deepwater technologies and services. The upgraded DTT features a 25-ft-wide screen powered by six high-resolution Barco projectors.
“With so many disparate groups and disciplines involved in deepwater projects, collaboration is absolutely fundamental to ensure that the project is carried out safely and successfully. The DTT is a good example of how the various groups can integrate and communicate,” Keith Tushingham, Schlumberger Information Solutions (SIS) DTT producer, said.
In April, the DTT was used to connect to the Schlumberger office in Aachen, Germany, to connect a client to the basin modeling experts. “Global tele-presence is common place today, but being able to transmit large amounts of data to remote locations is a different matter,” he said. “That requires good latency connectivity and cloud-based collaboration capabilities. This is the difference that the DTT brings to an organization”
Schlumberger will open another DTT in Kuala Lumpur in July to serve the Asia market, and other centers are planned for Oslo, London, Dubai and Calgary by the end of this year. Each center will address specific regional challenges.
“As SIS is focused on these industry challenges, it’s catalyzed a broader integration across our organization,” Mr Tushingham stated. “This allows us to integrate and get access to the breadth of all our expertise.”