Probabilistic methods for reserves estimation, including uncertainty quantification and probabilistic aggregation, have gained widespread acceptance in the oil and gas industry, since the first comprehensive guidelines were issued by the Society of Petroleum Engineers (SPE) in 2001. The probabilistic methods now used in the oil industry, as proposed in these guidelines, are similar to those also used in portfolio theory and risk management by the finance industry. A significant amount can be learned from the extensive experience with probabilistic methods and quantification of risk with measures [e.g., value-at-risk (VAR)] in financial risk management. Especially, the guidelines issued by the Basel II Accord (Bank for International Settlements 2006) and the discussions since the 2008 financial crisis contain important lessons.
In this paper, we examine a fundamental question: "Is the P90 reserves value an appropriate measure for quantifying the reserves' downside?" For the P90 reserves value to be considered a good measure of the reserves' downside, it needs to possess a number of basic characteristics involving P90 reserves for each field and the probabilistically aggregated P90 reserves for the portfolio of fields. Analogous to the definition of a coherent risk measure used in the finance industry, we define these characteristics for P90 reserves.
The P90 reserves are as good a risk measure as VAR used in the financial industry. However, like VAR, it is not a coherent risk measure. A possible uncertainty scenario, in which one of these necessary characteristics does not hold, is given. An alternative measure of risk for quantifying the reserves' downside, defined as the average reserves over the confidence interval higher than P90, is presented. This is a coherent risk measure.
In this paper, we highlight the appropriateness and limitations of using the P90 reserves estimate as a measure of the reserves' downside. Understanding of the limitations posed by using the P90 reserves value is vital in management of reserves risk.
Kheshgi, Haroon S. (ExxonMobil Research and Engineering Company) | Thomann, Hans (ExxonMobil Research and Engineering Company) | Bhore, Nazeer A. (Exxon Mobil Corporation) | Hirsch, Robert B. (ExxonMobil Gas and Power Marketing Company) | Parker, Michael E. (ExxonMobil Production Company) | Teletzke, Gary (ExxonMobil Upstream Research Company)
Focus on carbon capture and storage (CCS) has grown over the past decade with recognition of CCS's potential to make deep CO2-emission reductions and that fossil fuels will continue to be needed to supply much of the world's energy demands for decades to come. How CCS will compare with other options in the future depends critically on the cost of CCS (the focus of this paper) and resolution of barriers to CCS deployment and costs and barriers for other emission-reduction options.
This paper provides a comparison of the cost of electricity of five power-generation options--coal-and-gas-combined cycle gas turbine (CCGT) with and without CCS and nuclear--and shows regions of carbon price and fuel prices where each can be economically viable.
Current cost estimates for coal CCS for nth-of-a-kind power-generation plant are in the USD 60 to 100/t of CO2 avoided, which is higher than some of the earlier CCS estimates, and higher than the generally accepted range of expected carbon prices in the next 2 decades. The high cost of coal CCS suggests that
Although coal or gas CCS is unlikely to be economical in power generation over the next 2 decades, subsidized demonstrations of CCS are likely to occur. In addition, components of CCS technologies will continue to be economically practiced in early-use segments [e.g., natural-gas processing and enhanced-oil-recovery (EOR) operations]. In the natural-gas-processing industry, CO2 separation cost is a fraction of the cost of CO2 capture in power generation because of its higher gas pressure, and the CO2 separation is typically necessary to monetize the natural-gas resource.
In contrast, CCS for most refinery and industrial emissions is expected to be significantly more costly than in power generation because the CO2 streams are typically smaller scale and more distributed than those from large power plants.
Realistic cost estimates for CCS and for other greenhouse-gas (GHG) mitigation options are an important input for focusing research, development, and demonstration addressing barriers to applications that show the greatest promise and for development of sound policy.