With the maturity of hydraulic fracturing technology, shale gas development boom has arisen in the United States. The successful exploitation of shale gas has made the United States the largest natural gas producer in the world. With the technological progress and the increasing proven reserves, shale gas exploitation will enter an explosive growth period in the future, which will push American natural gas production into a "golden age".
The data shows that in 2000, shale gas production was less than 1% of American natural gas supply, and now it accounts for 30%, and its share is still rising. Thanks to the large-scale development of shale gas, in 2009, the United States replaced Russia as the world's largest natural gas producer, accounting for 20% of the global natural gas output. In 20 12, the sales volume of natural gas in the United States reached 71600 million cubic meters, an increase of 30% over 2006.
Affected by the successful development of shale gas in the United States, the global shale gas exploration and development has developed rapidly. Mexico plans to invest $2 billion to develop shale gas in the next two years. More than 40 multinational oil companies have been looking for shale gas in Europe, ExxonMobil has started drilling in Germany, Chevron and ConocoPhillips have started exploration in Poland, Austria's OMV has been testing the geological structure near Vienna, and Shell has targeted the shale gas exploration in Sweden. Russia is a large energy supplier. Although its conventional natural gas reserves are extremely high, it is still preparing to exploit shale gas. Asian countries such as Indonesia and South Africa in Africa are planning the development of shale gas to varying degrees.
Shale gas has become a new favorite, which not only profoundly affects the natural gas market structure, but also begins to change the fate of some high-energy heavy chemical industries in the United States. Due to the obvious drop in energy costs, the chemical and manufacturing industries in the United States have experienced a phenomenon of "backflow" and their industrial competitiveness has improved.
In China, according to the shale gas development plan (20 1 1-20 15), during the 12th Five-Year Plan period, China will complete the proven shale gas geological reserves of 600 billion cubic meters, the recoverable reserves of 200 billion cubic meters, and realize the shale gas output of 6.5 billion cubic meters in 20 15 years, and strive to reach shale gas in 2020. If this goal is achieved, the self-sufficiency rate of natural gas in China is expected to increase to 60% to 70%, and the proportion of natural gas in primary energy consumption in China will increase to about 8%. This will help to reverse China's energy structure that relies too much on coal and reduce its external dependence on energy. Shale gas exploitation technology mainly includes horizontal well technology, multi-layer fracturing technology, clean water fracturing technology, repeated fracturing technology and the latest synchronous fracturing technology, which are constantly improving the output of shale gas wells. It is the successful application of these advanced technologies that has promoted the rapid development of shale gas development in the United States. If these advanced technologies can be introduced, it will contribute to the development of shale gas in China.
Shale gas development technology in China has been continuously improved: one is drilling technology, and 3500m shale gas well and 2000m horizontal drilling can be completed in 45 days at the earliest. Second, the separate drilling fracturing technology has been completely mastered and basically realized localization. Although adsorption and free phase natural gas exist at the same time, the development of shale gas does not require drainage and depressurization. Due to the extraction of free phase natural gas from shale, the pressure can be naturally reduced, and the adsorbed phase and a small amount of dissolved phase natural gas can be dissociated, so as to further improve the natural gas production capacity and realize long-term stable production. Because the productivity and recovery rate of low porosity and low permeability natural gas are also low, the final recovery rate of rock gas depends on effective fracturing measures, and fracturing technology and production technology directly affect the economic benefits of shale gas wells.
Some experts mentioned root-edge gas, and J.A.Masters (1979) put forward the idea of deep bugas gas, established a gas-water inversion model, and described the broad prospect of natural gas exploration and development. Because of the difficulty in identification, P. R. Rose et al. (1986) put forward the central gas in the basin, and B.E.Law et al. improved the identification method of this kind of gas reservoir from "regional gas-water inversion" to "boundless water", thus simplifying the complicated identification process and greatly advancing the identification time of this kind of gas reservoir. Because there are still a lot of drilling geological data to determine "boundless bottom water", it is still not the best scheme.
Through experimental research, it is determined that root gas is the natural gas accumulation directly connected with gas source rocks in tight sandstone, and the gas-bearing property at the bottom of sandstone is emphasized. Because the natural gas adjacent to the gas source rock (root) and formation water form a continuous medium with direct transmission in migration force, it is regarded as root-edge gas. The main body of this kind of gas reservoir is formed after sandstone is generally densified, which roughly corresponds to the pyrolysis stage of coal measures and dark mudstone and the pyrolysis gas stage of oil, so the burial depth is generally relatively large.
Based on the dynamic principle of natural gas accumulation, the research method of root-edge gas advances the gas reservoir identification technology to the single well profile, that is, whether the gas-bearing characteristics at the bottom of sandstone appear and develop (completely different from the gas-bearing patterns and characteristics at the top of sandstone in conventional traps), so as to quickly identify the gas reservoir types in the earliest stage of exploratory wells (rather than pre-exploration wells or even development wells). Only the gas content at the bottom of sandstone can explain the continuity of natural gas accumulation dynamics, further elaborate the mechanism characteristics of natural gas accumulation, and thus determine the types of natural gas accumulation mechanism, that is, there are deep basin gas, basin central gas, marginal gas and even syncline gas or full basin gas, and determine the characteristics of natural gas accumulation, enrichment and distribution, and extend the time for identifying gas reservoir types to the maximum time for subsequent exploration ideas. Shale gas has changed the energy structure of the United States, but it has also brought a series of potential problems, such as water consumption and pollution.
Reporter Yang Jianfa from Washington The United States is the earliest and most successful country in shale gas development. Due to abundant reserves and advanced development technology, the development of shale oil and gas resources in the United States has gradually become a scale. 20 1 1 year, its shale gas production reaches180 billion cubic meters, accounting for 34% of the total natural gas production in the United States. Some experts predict that with the supplement of shale gas, the natural gas in the United States will be enough 100.
However, although shale gas has reduced the external energy dependence of the United States, there are still many disputes about the large-scale development of shale gas in the United States. Shale development has helped the United States become a major oil and gas country.
The United States is rich in unconventional energy reserves. According to us energy information administration's data, shale gas, tight sandstone gas, coalbed methane and other unconventional energy natural gas reserves account for 60% of the exploitable natural gas reserves in the United States.
According to the data released by api gravity, including shale gas resources, the United States ranks first in the world in terms of oil and gas resources that meet the mining standards, 24% more than Saudi Arabia.
Since 1990s, with the support of domestic policies and technological progress, the United States has taken the lead in exploring and developing unconventional energy sources such as shale gas. After that, the progress of hydraulic fracturing and horizontal drilling technology in the United States solved the technical and cost challenges of extracting oil and gas from shale, and the development of shale gas in the United States gradually took shape.
In 2000, the shale oil in the United States was only 200,000 barrels per day, accounting for only 3% of the total domestic output, while in 20 12, it was 6.5438+100,000 barrels per day. The shale gas production in the United States also surged from 654.38+0.22 billion cubic meters in 2000 to 654.38+0.378 billion cubic meters in 2065.438+00.
Cambridge Energy Consulting predicts that by the end of 2020, the United States will produce 3 million barrels of shale oil every day, more than half of the crude oil production in 20 12 years. According to the data of PFC energy consulting company in the United States, shale oil and gas resources will account for about one-third of US oil and gas production by 2020, when the United States will surpass Russia and Saudi Arabia and become the largest oil and gas producer in the world. It is resisted because it wastes water and is easy to pollute.
The development of shale gas has changed the energy structure of the United States. In the past decades, coal-fired power generation has been the main source of electricity in the United States, accounting for 53% in 2003. However, with the development of shale natural gas, a large number of cheap natural gas appeared in the market, which led to the closure of many coal-fired power plants and the rise of natural gas power plants. 20 1 1 In the first nine months, the proportion of coal-fired power generation decreased to 43%, while the proportion of natural gas power generation increased from less than 17% in 2003 to about 25%. However, shale gas has also caused a series of potential problems.
First, it consumes a lot of water resources and cannot be recycled. The hydraulic fracturing technology used in shale gas mining needs to consume a lot of water resources, so oil and gas developers begin to seize agricultural water and even occupy municipal water. It is reported that irrigation of 640 acres (about 2.6 square kilometers) of arid land requires 407 million gallons (about 65.438+54 million liters) of water, and corn worth 200,000 US dollars can be harvested. If the same amount of water is used for hydraulic fracturing drilling, oil worth 2.5 billion dollars can be obtained. Because the water used for drilling is injected into shale formation much deeper than the underground aquifer, it is mainly absorbed by rocks and cannot be recycled.
Developing shale gas is also easy to cause environmental pollution. Shale oil and gas exploitation must pass through the aquifer during drilling, and the chemical additives used in drilling will pose a pollution threat to groundwater. In May of 20 10, two major leakage accidents occurred in Keystone pipeline, which mainly transported heavy oil extracted from oil sands, causing serious pollution and ecological damage.
It is precisely because of many hidden dangers that American environmental protection groups and farming and animal husbandry groups strongly oppose the development of unconventional oil and gas resources, and the Obama administration has also delayed the implementation of the "keystone" pipeline extension project.