One of the most significant petroleum exploration frontiers in North America is the deepwater Gulf of Mexico (GoM), where operators in recent years have announced a number of major discoveries.

Developing deepwater fields is a substantial technical and economic challenge. Most recent ultra-deepwater discoveries have not yet been brought into production.

It may therefore seem a little odd that industry and the US Federal Government are already working on improved oil recovery (IOR) for undeveloped fields. However, it is readily apparent that technology breakthroughs will be required before IOR processes can be successfully applied in deep water. The first question is where to focus the limited available research funds.

On Feb. 3, following a competitive bidding process, the Research Partnership to Secure Energy for America (RPSEA) awarded an 18-month, US $2 million contract to Houston-based Knowledge Reservoir, LLC to lead a study on IOR for deepwater and ultra-deepwater assets in the GoM. Knowledge Reservoir’s academic partner on the project is Louisiana State University in Baton Rouge, La., and its industry partner is Anadarko Petroleum Corp., which is funding 20% of the project costs through an in-kind contribution of laboratory data from its current K2 deepwater GoM field development.

RPSEA is a non-profit consortium with more than 145 members including 25 of the premier research universities in the US, five US national laboratories, other major research institutions, large and small energy producers, and energy consumers. Its mission is to provide a stewardship role in ensuring the focused research, development, and deployment of safe, environmentally sensitive technology that can effectively deliver hydrocarbons from domestic resources to the citizens of the US.

RPSEA was chosen by the US Department of Energy’s National Energy Technology Laboratory to manage a public-benefit research program set up by the US Congress in the Energy Policy Act of 2005, funded from lease bonuses and royalties paid by industry to produce oil and gas on Federal lands.

Knowledge Reservoir’s project is a component in RPSEA’s long-term road map. Its ultimate aim is to identify improved recovery opportunities in the early stages of field development planning.

A key outcome of the current study will be the identification of “technology gaps” — areas where technological breakthroughs could make significant incremental oil recovery possible in the very challenging deepwater environment.

Study approach

The work plan includes four major components (Figure 1):
• Build a resource database characterizing deepwater and ultra-deepwater reservoir assets, and identify the key reasons why remaining hydrocarbons are projected to be left unrecovered in such reservoirs.
• Conduct a comprehensive worldwide review of IOR processes, experiences, and best practices, both on and offshore. From this review, develop methodologies for quantifying the potential incremental recovery from application of key IOR processes.
• Based on the above two foundational building blocks, quantify the potential incremental oil recovery which might be deliverable using key IOR processes — if the technological barriers to implementing them in deepwater GoM fields could be overcome. IOR processes will then be ranked based on the incremental volumes they could potentially deliver and on the perceived difficulty of closing the technology gaps.
• For the most promising IOR processes, identify possible ways to close technology gaps, tapping into the ideas of experts from operating companies, service companies, national laboratories, and academia through blue-sky brainstorming sessions. After appropriate analysis, recommend the most promising concepts for further research.
IOR in deep water

The definition of IOR has long been controversial within the industry. IOR is seen as being a broader term than enhanced oil recovery (EOR). When applied to deepwater (more than 1,000 ft) and ultra-deepwater (more than 5,000 ft) GoM, the practical definition of IOR may be even broader.

Ultimate recovery is affected by processes that happen at the pore level in reservoirs. But it is also affected by processes that happen at the reservoir level (e.g., sweep efficiency), in the near wellbore region (e.g., stimulation), in the wells themselves (e.g., artificial lift), and in seabed flowlines and surface facilities (e.g., corrosion control). In the harsh environment of deep water, all of these processes are part of IOR.

Deepwater and ultra-deepwater fields can be very large; Thunder Horse and Mars have in excess of 1 Bbbl original oil in place (OOIP). However, many individual reservoirs are quite small due to the presence of multiple sands and compartmentalized reservoirs.

It was reported that 151 out of the 211 reservoirs in this sample have OOIP less than 50 MMB, and another 30 have OOIP between 50 and 100 MMB. Thus, 85% of the reservoirs in this sample have less than 100 MMB OOIP each, but together they account for 39% of the total OOIP. Part of the challenge for improving oil recovery in the GoM is making it work in smaller reservoirs.

The project team has begun by casting a very broad net and, so far, has identified almost 60 IOR processes for consideration, ranging from artificial lift methods to microbial EOR. As the study proceeds, this list will be whittled down to a group of key IOR processes. For those, the aim is to develop methodologies for making screening-level predictions of potential incremental recovery when applied to specific GoM reservoirs.

GoM resources

According to the MMS, estimated ultimate recovery from proved fields in the deepwater GoM is about 9 Bbbl, which implies an OOIP of around 30 Bbbl and a target for IOR of around 20 Bbbl projected remaining oil in place at abandonment. In addition, the MMS estimates the undiscovered technically recoverable resources of the GoM Outer Continental Shelf at around 45 Bbbl. Clearly, there is a substantial remaining oil in place target for IOR in the deepwater GoM.

To put these volumes in perspective, the National Petroleum Council estimated that OOIP in the largest 2,500 onshore reservoirs in the US was about 325 Bbbl. Much of this oil will remain in the ground after primary and secondary production.

The current project will make use of Knowledge Reservoir’s “ReservoirKB” Web-based database of public-domain data on fields and reservoirs in the deepwater and ultra-deepwater GoM. The plan is to assemble key reservoir parameters from ReservoirKB and other sources, and use them as inputs to the screening-level methodologies for estimating the IOR potential for specific processes in specific reservoirs.

Ultimately, this study will provide RPSEA with well-justified, prioritized recommendations on where to invest its R&D funds. And the world will have taken one small further step down the long road towards maximizing ultimate recovery from the hydrocarbon resource base, in the GoM and beyond.