A new type of unconventional natural gas resources: Overpressure-dissolved gas

China's conventional and unconventional natural gas resources: Potential and exploration targets

Assessment of global unconventional oil and gas resources

As conventional gas resources are depleted, unconventional gas (UG) resources (gas from tight sands, coal beds, and shale) are becoming increasingly important to U.S. and world energy supply. The volume of UG resources is generally unknown in most basins outside North America. However, in 25 mature North American basins, UG resources have been produced for decades, and resources and reserves are well characterized. The objective of this work was to evaluate recoverable UG resources and determine the quantitative relations between known conventional and unconventional hydrocarbon resources in mature North American basins, with the goal of using these relations to estimate unconventional hydrocarbon resources in basin outside North America, which we call frontier basins.We used data from the U.S. Geological Survey, Potential Gas Committee, Energy Information Administration, National Petroleum Council, and Gas Technology Institute to evaluate relations among hydrocarbon resource types in the Appalachian, Black Warrior, Greater Green River, Illinois, San Juan, Uinta-Piceance, and Wind River basins. We chose these seven basins for preliminary analysis of relations between conventional and unconventional gas resources because they are mature basins for both conventional and unconventional oil and gas production. To conduct this analysis, we wrote a computer program that we call PRISE (Petroleum Resources Investigation Summary and Evaluation). Input data for PRISE, obtained from the published data sources, were the values of technically recoverable resources, which were the sum of the following resource categories: cumulative production, proved reserves, growth, and undiscovered recoverable resources. We then compared technically recoverable conventional and unconventional resources for each basin to evaluate relationship between conventional and unconventional resource volumes in these seven basins.For the seven basins studied, we found that 10% of the total recoverable hydrocarbon resources are conventional oil and gas, whereas 90% of the recoverable hydrocarbons are unconventional resources. We propose that the results of this study may be used to estimate recoverable resources from unconventional gas reservoirs in target (frontier) basins, where conventional oil and gas resources are known but unconventional resources have not been evaluated.

Surge in the worldwide demand for natural gas, in recent years, has resulted in a considerable interest in the unconventional natural gas resources in many countries, including Saudi Arabia. Numerous studies indicate that the supply and demand balance can be achieved through the exploitation of unconventional resources which are located in the major hydrocarbon basins of the world. The scope of this paper is to review the main sources of unconventional natural gas with some emphasis on potential resources in the Arabian Peninsula, and to present initial results derived from a recent study of Paleozoic formations in the Rub’ Al-Khali Basin. Besides contributing to the general knowledge on unconventional natural gas resources, the information provided in this paper is expected to guide current exploration activities on the unconventional natural gas in Paleozoic formations in the Rub’ Al-Khali Basin. Based on the lognormal model, it has been demonstrated that the volume of unconventional gas resources in a particular basin is several times that of the proved reserves in that basin. Considering this model, it is possible to deduce that vast amounts of unconventional resources exist in the Arabian Peninsula. Potential targets have been identified to be the Paleozoic formations, including Qasim, Sarah, Qalibah, Jauf, Unayzah, and Khuff. Average porosity and permeability measurements, based on the combined data from several vertical wells intersecting each formation in the Rub’ Al-Khali Basin, have been compared with the corresponding published data from the producing tight gas formations from North American basins. Porosity and permeability values, representing various formations in the Rub’ Al-Khali Basin, compare well with the corresponding parameters from North American basins. The same data, also, revealed the differences and similarities of patterns of distributions of petrophysical parameters in formations under consideration. Major technical contributions of this paper include: (1) appraisal of distribution of unconventional natural gas resources in the Arabian Peninsula, (2) characterization of natural gas potential of various formations, and (3) comparison of petrophysical parameters with the corresponding values from similar basins from North America.

Summary As conventional gas (CG) resources are depleted, unconventional gas (UG) resources (gas from tight sands, coalbeds, and shale) are becoming increasingly important to US and world energy supply. The volume of UG resources is generally unknown in most basins outside North America. However, in many mature North American basins, UG resources have been produced for decades, and resources and reserves are well characterized. The objective of this work was to determine the quantitative relations between known conventional and unconventional hydrocarbon resources in mature North American basins, with the ultimate goal of using these relations to estimate UG resources in frontier basins outside North America. We used assessments by the US Geological Survey (USGS), Potential Gas Committee (PGC), Energy Information Administration (EIA), National Petroleum Council (NPC), and Gas Technology Institute (GTI) to evaluate relations among hydrocarbon-resource types in the Appalachian, Black Warrior, Greater Green River, Illinois, San Juan, Uinta-Piceance, and Wind River basins. We chose these seven basins for initial analysis of relations between CG and UG resources because they are mature basins for both conventional and unconventional oil and gas production. To conduct this analysis, we wrote a computer program that we call Petroleum Resources Investigation Summary and Evaluation (PRISE). Input data for PRISE, obtained from published data sources and resource assessments, were values of technically recoverable resources, consisting of the following resource categories: (1) cumulative production, (2) proved reserves, (3) probable and possible reserves and contingent resources (PPC), and (4) prospective resources. We then analyzed these data in each of the seven basins to assess the relationship between conventional- and unconventional-resource volumes. For the seven basins studied, we found that approximately 10-20% of the total recoverable hydrocarbon resources are conventional oil (CO) and CG, whereas 80-90% of the recoverable hydrocarbons are UG resources. We suggest that the results of this study may be used to estimate recoverable resources from UG reservoirs in frontier basins worldwide, where CO and CG resources are known but UG resources have not been evaluated.

There are substantial volumes of unconventional gas resources in China, including tight gas sands and coal bed methane (CBM). Rapid economic growth in China has increased the demand for more sources of clean energy, such as natural gas from unconventional reservoirs. In the 1980's in North America, the combination of federal tax credits and various technical development programs sponsored by private organizations, public companies and government agencies fostered the development of technology for unconventional natural gas exploration and exploitation. As those technologies in geology, geophysics, drilling, completion, and production have matured, and the price for natural has increased, the development of unconventional natural gas has been blossoming for last decade globally. Without question, it is certain that the development of unconventional natural gas in China will be blossoming in the coming decades. However, there are significant challenges and hurdles to overcome before that happens. This paper first analyzes the conditions and environment required to ensure the development of unconventional natural gas sources, including price, the service industry, cost, and the operational environment. We focus on key technologies in geology, geophysics, and engineering, and how they are tied to the success of unconventional natural gas development. The paper also discusses the advantages China offers, and the challenges in China that must be over come to be sure the blossom of the unconventional natural gas development actually occurs. On the basis of the author's operational experience both in China and North America, we will discuss the impact of different operational environments on unconventional gas development. The paper also discusses: The impact of new technology on unconventional natural gas development; The technologies available and unavailable in China for unconventional natural gas development, and how to use and develop those technologies; and The role of foreign operators in developing unconventional natural gas reservoirs in China. The paper concludes that an open, competitive, and mature service sector is critical to the future blossom, and that proper government regulations and policies in pricing and taxes, and downstream infrastructure will impact the development of unconventional natural gas resources.

Hydrocarbon generation and expulsion characteristics of the Lower Cambrian Qiongzhusi shale in the Sichuan Basin, Central China: Implications for conventional and unconventional natural gas resource potential

Unconventional gas accounts for more than 40% of U.S. domestic gas production and more than 10% of world output. The amount of resources available is still uncertain and estimates vary to a large degree. In this paper, unconventional gas resources within the United States will be examined. This paper will take a brief look at all types of unconventional gas resources (there have been 6 identified) but will concentrate on shale gas and coal-bed methane, as they are the resources receiving the most attention. This paper will also delve into the technology in unconventional gas production and exploration, including recent innovations in the industry. Finally, environmental concerns unique to unconventional gas production will be addressed. Natural gas refers to naturally occurring hydrocarbons found trapped underground. It occurs as mixtures of hydrocarbons of various molecular weights (methane, butane, etc.) and was formed millions of years ago from fossilized organic matter. Natural gas can be used as a cleaner burning alternative to other fossil fuels for power generation. It produces half the amount of carbon dioxide as coal and roughly 25 percent less carbon dioxide than gasoline. Consequently, it is becoming more popular in today's environmentally conscious world. Worldwide demand is expected to increase at twice the rate of oil until at least 2030. Interest in natural gas is at an all-time high in the United States. Only recently have we learned about the vast unconventional resources that exist within our borders. The implications for reduced dependence on foreign sources of gas are promising for the future of this country. There may be sufficient resources within the United States to allow this energy source to thrive for many years to come. Natural gas can be divided into two categories: 1) Conventional gas which is found in reservoirs where the gas has been trapped by a layer of rock. Usually conventional gas refers to that which exists on top of crude oil reservoirs. Conventional gas is relatively easy to extract because once a well is drilled, the gas will naturally flow to the surface. 2) Unconventional gas which is referred to gas trapped in formations where it cannot easily flow such as in shale formations; or, gas that is tightly attached to the surface of the surrounding rock such as in coal-bed seams. Unconventional gas is more difficult to extract because it often requires fracturing the rock formation to allow the gas to accumulate in sufficient quantities and flow out of the well. There are six types of unconventional gas resources: shale gas, coal-bed methane, deep gas, tight gas, geopressurized zones, and methane hydrates. Each of these unconventional gas resources within the United States will be examined with a focus on their development and the unique challenges facing them.

This paper provides some context and an empirical basis to evaluate the historical and potential impact of Section 29 production tax credits on the development and production of unconventional gas resources (UGR). The data, analyses and conclusions reported here are based on studies conducted for government and industry clients over the past two years. The federal government implemented incentive pricing and Section 29 production tax credits over a decade ago as the principal policy tools to accelerate development of UGR. Given the large expected potential contributions of tight gas, coalbed methane and Devonian shale gas, these incentives were designed to reduce risk and improve project economics of these "high-cost" gas resources. Despite the fundamental transformation of the gas industry over the past decade, however, the Section 29 credit has not changed in scope or mechanism since its inception in 1980. Critics of the credit allege that, during a time of significant changes in the characterization of the gas resource base, extraction technology effectiveness, gas markets, wellhead prices, and pipeline regulation, the credit has changed from a modest incentive to a major cause of market distortion. The results of two recent studies are discussed that provide a basis for more rational debate about the merits of eliminating or extending the credit, in either its current or an alternative form. The first study1 addressed allegations that Section 29 credits were responsible for widespread wellhead gas price declines in 1991. After looking at supply, demand, transportation and market behavior for UGR-prone basins during 1991, we conclude that Section 29 credits had only a minor direct affect on wellhead prices. The second study2 addressed the potential for an alternative configuration of the credit to restore the credit's originally intended impact. Alternative configurations of the credit are offered as a means to adhere to original Congressional intent for the credits, maximize efficiency and equity and minimize costs to the U.S. Treasury. Selection of an optimum credit configuration, however, first requires a clear specification of federal policy objectives.

To meet future global oil and gas demands, the energy industry will need creative thinking that leads to the discovery and development of new fields. Unconventional gas resources, especially those in frontier (exploratory) basins, will play an important role in fulfilling future energy needs. To develop unconventional gas resources, we must first identify their occurrences and quantify their potential. Basin analog systems investigation (BASIN) is a computer software that can rapidly and inexpensively evaluate the unconventional gas resource potential of frontier basins. BASIN is linked to a database that includes petroleum systems and reservoir properties data from 25 intensely studied North American “reference” basins that have both conventional and unconventional oil and gas resources. To use BASIN, limited data from a frontier or “target” basin are used to query the database of North American reference basins and rank these reference basins as potential analogs to the frontier basin. Based on analog comparisons, we can predict unconventional gas resources and make preliminary engineering decisions concerning resource development and the best drilling, completion, stimulation, and production practices to use in the frontier basin. Initial software validation shows consistent results. If a basin is selected as the target basin while the same basin is also in the reference basin list, the results show that the basin is a 100% analog to itself. Other basins in the reference basin list are less than 100% analogs. Also, BASIN performed favorably when it was tested against analog basin decisions made by of a team of industry experts. BASIN rapidly and inexpensively identifies and ranks reference basins as analogs to a frontier basin, providing insights to potential gas resources and indicating the preliminary best engineering practice for resource development. It is an effective tool that provides guidance to inexperienced professionals and new perceptions for seasoned experts.

The demand for energy is increasing along with the rise in population. Indonesian people rely on conventional resources such as coal, oil, and natural gas to meet their energy needs. It is estimated that coal can only be exploited for up to 61 years, natural gas for 34 years, and oil for 19 years. Meanwhile, Indonesia possesses unconventional oil and gas resources (e.g., coal bed methane (CBM), tight gas, shale gas and oil, and methane hydrate), estimated to reach 1,800 trillion cubic feet (TCF). These resources are in the exploration stage and have yet to be fully exploited due to technological limitations. Nevertheless, the Indonesian government continues to emphasize the development of this type of energy resource. Therefore, this study conducts a review of the potential of unconventional oil and gas resources in Indonesia, covering characteristics, potential occurrences in Indonesia, exploitation methods, utilization as a source of energy, and opportunities and challenges in their application. The method used is a narrative review based on secondary data by examining papers published in reputable national and international journals in the last ten years. Results show that unconventional oil and gas resources have different characteristics, including permeability, porosity, and depth. CBM can be found at the shallowest depth, followed by tight gas, methane hydrate, and the deepest is shale gas. Potential occurrences of these resources in Indonesia include gas hydrate (858.2 TCF), then shale gas (574.07 TCF), coal-bed methane (453.3 TCF), and shale oil 11.24 million tons. Exploitation can be done in various ways, such as dewatering for CBM, hydraulic fracking for tight and shale, and depressurization for methane hydrate. Once exploited, methane gas can be used for power plants, vehicle fuel, and industrial and household needs. Opportunities and challenges from various aspects, as well as applicable laws in Indonesia, are also discussed. In this light, the contribution of our study is to provide a comprehensive review of the characteristics, location, exploitation methods, opportunities, and challenges of utilizing unconventional oil and gas resources in Indonesia.

Chapter 1 - Overview of Natural Gas Resources

RPSEA is currently in its first year of performance under contract DE-AC26-07NT42677, Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources Program Administration. Progress continues to be made in establishing the program administration policies, procedures, and strategic foundation for future research awards. Significant progress was made in development of the draft program solicitations. In addition, RPSEA personnel continued an aggressive program of outreach to engage the industry and ensure wide industry participation in the research award solicitation process.

The rapid development of natural gas lays the foundation for the unconventional gas development. In 2015, unconventional natural gas production is 44.9Bcm, accounting for 34.06% of total natural gas production. Increasing demand of natural gas provides a wide developing space for unconventional natural gas. China has deployed unconventional natural gas resource evaluation to different extent, which mainly includes tight gas, CBM and shale gas. Unconventional gas E&P in China is still in its initial stage. By 2015, 1.6 Tcm proved reserves and 36 Bcm production has made China tight gas entering a large scale and commercializing stage. CBM development is still in the initial stage of E&P, with less reserve and production, in the early stage for commercialized development. Shale gas has a significant breakthrough since its proved reserves reached to 544.1Bcm, and production reached to 4.5Bcm. At present, conventional gas develops rapidly in China. During the next 5-10 years, it will also take the dominant position in the natural gas development. Unconventional gas will play a more and more important role in the long-term development of natural gas.

Distribution and potential of global oil and gas resources