Research Funded by DOE/RPSEA Advances Ultradeepwater Technology
Roy Long, National Energy Technology Laboratory, United States Department of Energy
A number of research projects awarded by the Research Partnership to Secure Energy for America (RPSEA), with funding and oversight by the United States Department of Energy’s National Energy Technology Laboratory (NETL), have shown solid potential to advance deepwater and ultradeepwater (UDW) oil and gas development.
The DOE/RPSEA projects are among more than 15 to be featured in a session on funding new E&P technologies on 7 May at the Offshore Technology Conference (OTC) in Houston. Chairing the session will be James Pappas, vice president of ultradeepwater at RPSEA. Nine of the technologies developed through this research are discussed herein.
One of the projects, highlighted on the cover of the January 2014 issue of JPT, is the Lockheed Martin Marlin autonomous underwater vehicle. This system has the following advantages over remotely operated vehicle (ROV) systems: 3D model generation in hours vs. days; the use of smaller vessels with fewer crew members; no need for umbilical management; real-time change detection, enabling on-site assessment of survey results and structural anomalies; rapid assessment capability of potential environmental damage; and the ability to generate accurate, geo-registered models for structural integrity assessment.
Also under consideration is the inclusion of high-resolution visual imaging to enable accurate subsea measurement of flow rate from a blowout or from ocean floor seeps for predrilling site investigations. The project is in its final phase of development and scheduled to be complete by June.
Another interesting set of projects deals with metocean issues that affect UDW development. Studies in this area have continued since the early days of UDW research and development within RPSEA. The first efforts studied the US Gulf of Mexico (GOM) loop currents to develop a better hurricane forecasting model, because these relatively warmer currents often increase hurricane intensity.
The goal of these projects was to develop a better long-range forecast (of up to 90 days) of hurricane activity in the GOM. The newer models with higher resolution potentially could better describe the density of the spiral rain bands caused by higher wind velocities farther from the center of the storm. The spacing of these bands appears to have a greater influence on the extent of damage sustained by an offshore vessel than hurricane classification or size, as the spacing more directly affects seawater wave height.
As project water depths continue to increase, major industry concerns are the weight and capabilities of umbilicals in developments planned in 10,000 ft to 12,000 ft of water. To address these challenges, RPSEA made two awards in the form of a “design-off” competition between GE Global Research and DeepFlex. Both companies successfully completed their Phase 1 design effort and are in Phase 2 prototype development.
A downselect, which would narrow the field of potential contractors, was initially planned at the conclusion of Phase 1. However, both designs offered technically different alternatives, each with its own advantages, for developing fiber-reinforced pipe capable of working at these water depths (Fig. 1). As a result, the downselect was delayed until the end of Phase 2 to establish constructability of each design and to verify basic performance properties of each prototype.
Other needs are being recognized for UDW development, as the distance required for subsea tiebacks continues to increase. As development concepts approach 100-mile tieback distances, a number of new requirements for subsea equipment and capabilities have arisen. One is to provide subsea power by means of high-voltage direct current in lieu of extended hydraulic systems. Thus, projects focused on subsea power distribution systems and ultrahigh conductivity power cables are in progress.
Under RPSEA’s project 08121-2901-01, “Ultra-Reliable Deepwater Electrical Power Distribution System and Power Components,” GE Global Research has conducted extensive design work and laboratory testing that indicate the feasibility of subsea electric power generation and distribution. However, additional work is needed to develop the appropriate power cables and high-power connectors.
Nanoridge Materials has been contracted to develop a novel approach for ultrahigh-conductivity power cables. The goal of this work is to use nanotechnology to develop a polymer-based cable with higher current-carrying capacity and lower resistivity than copper at one-sixth the weight.
Among the many challenges to UDW operations are corrosion and scale in extreme environments. Deeper project settings in the GOM are predicted to exceed 200°C and 20,000 psi. Impact on high-strength materials and inspection requirements could be significant. To improve understanding of the problem, its extent, and potential mitigation strategies, Brine Chemistry Solutions (BCS) was awarded project 10121-4204-01, “Corrosion and Scale at Extreme Temperature and Pressure.” The goal of the project was to extend testing capabilities and theory to 24,000 psi and 250°C.
In addition to developing a unique experimental design, which includes high-resolution 3D imaging of surfaces by means of a vertical scanning interferometry process, BCS developed a novel modeling theory that should advance prediction and inspection efforts. Phase 1 of the project was just completed. Phase 2 will continue to verify recently developed prediction capabilities and include an investigation process called “molecular simulation.” Phase 2 is scheduled to conclude in August 2015.
Flow assurance continues to be a major concern in UDW subsea operations, and has been reflected in the RPSEA Subsea System portfolio since the program began. A project initiated in August 2008 (07121-1301, “Improvements to Deepwater Subsea Measurements”) identified critical research needed to close key flow measurement gaps. As a result, another project (10121-4304-01, “More Improvements to Deepwater Subsea Measurements”) was initiated in July 2012 to address some of those gaps. The project’s goal was to develop prototype systems and approaches to “reliably and economically identify and assess flow and well production or well control events and conditions for the purpose of preparing the appropriate response actions.” A number of key tasks were identified to help achieve this goal:
- Subsea sampling: in-situ testing of a subsea sampling system and standardized production fluid interface (developed in 07121-1301), using live production fluids, and revision of a document on best practices for sampling to consider sample point location and sample line effects
- ROV-conveyed measurement: investigation of three key ROV‑conveyed flow measurement technologies: 1) subsea ROV deployment of “wet” sensors into pipeline flow; 2) subsea ROV clamp-on measurement; and 3) a lower marine riser package early kick detection system that monitors mud density
- Downhole high-pressure/high-temperature (HP/HT) measurement: addressing the need to accurately measure well flow rate downhole in HP/HT conditions by developing a novel differential pressure sensor
- Evaluation of flow modeling: evaluating a virtual flow meter model for detecting and evaluating a flow or well control event in real time, and making recommendations for future flow model development
- Diagnosis of meter fouling: identification of ways to detect fouling in multiphase and wet gas meters so that corrective measures can be taken before large errors occur
The flow assurance research is one of the longer, more complex projects in the program. Phase 2 will be completed in July, and the final phase is scheduled to conclude in July 2015.
One of the most interesting recent projects from the drilling and completions portfolio was the development of a gyroscope package for directional drilling, based on a microelectrical mechanical system (MEMS), which is small and rugged enough to be placed next to the drill bit (Fig. 2). Project 09121-3500‑10, “Gyroscope Guidance Sensor for Ultra-Deepwater Applications,” resulted in a system developed by Laserlith. It includes a demonstrated gyroscope mechanical sensor design integrated with robust readout circuits that can operate in downhole high-temperature and high-vibration/shock environments.
The MEMS gyroscope enables the inertial guidance system to be positioned next to the drill bit, providing a significant improvement over existing magnetometer guidance systems installed 50 ft to 80 ft behind the drill bit.
Cement integrity has become another crucial issue in post-Macondo deepwater and UDW operations. Since 2010, the RPSEA portfolio has been increased by three cementing projects in the RPSEA-contracted program and one project in the NETL’s complementary research program. In the contracted program, those projects are
- 10121-4501-01, “Smart Cementing Materials and Drilling Muds for Real-Time Monitoring of Deepwater Wellbore Enhancement”
- 10121-4502-01, “Deepwater Reverse-Circulation Primary Cementing”
- 10121-4504-01, “Intelligent Casing-Intelligent Formation Telemetry (ICIFT) System”
An additional cementing project in NETL’s complementary program is titled “Improving Science-Base for Wellbore Integrity, Foam Cements.” This study uses an industrial strength computerized tomography (CT) scanner to evaluate foam cement samples captured under pressure in a simulated field setting. These samples are scanned for various service companies to evaluate the homogeneity of the foam cement coming out of the blender after it has traveled a short distance (60 ft to 70 ft) down the pipe and been captured in a collection cell.
The CT scanner and related software have unprecedented analysis capabilities, including bubble size, size distribution, bubble count, and overall dispersion of bubbles to show a relative quality of the cement.
NETL’s lead researcher, Barbara Kutchko, is working with the American Petroleum Institute and various service companies in a joint industry project that is gathering momentum to further evaluate and improve foam cementing technology and practices.
There are several interesting aspects of the three contracted cement projects noted above. One of the most promising technologies is a breakthrough in nano materials. Adding these materials to cement mix water can improve cement properties. This process is being developed for oil and gas operations by means of a fourth cementing contract awarded through NETL’s Strategic Center for Natural Gas and Oil to Oceanit, which patented the basic process in 2006. Oceanit is commercializing the specialized cement for rugged applications, such as vehicle scales for various state transportation departments. The performance properties (Table 1) have the potential to improve cement barrier reliability in oil and gas wells, and the nano materials allow the cement to be interrogated electronically to determine the cement’s condition over time.
At the end of 2013, the US Congress repealed the Energy Policy Act of 2005, thus terminating government funding for RPSEA and the technology research projects supported under the act. While many of the projects have funding through the next couple of years, arrangements are now being sought to establish continuing oversight for ongoing projects. The projects described in this article are a small representation of those projects spanning the past 7 years carried out under the act’s subtitle for UDW, unconventional natural gas, and other petroleum resources research.
In addition to the session chaired by Pappas, OTC will hold a session on 6 May on the evolution of deepwater technology at which Kelly Rose, technical coordinator of the NETL UDW complementary research program, will provide an overview of the results from the program’s research. Project presentations will focus on the following key areas of the UDW portfolio: drilling and completion operations; surface systems and umbilicals; and subsea systems reliability.
For more information, visit the NETL at www.netl.doe.gov and RPSEA at www.rpsea.org, or contact Pappas (firstname.lastname@example.org). Project updates are also available at the RPSEA UDW quarterly technical advisory meetings and the RPSEA UDW Conference this fall, which will be scheduled shortly.