Hydraulic fracturing recipe for disaster ?

"Now all the fractured gas reservoirs are water power , but I'm here to make an appeal , do not water fracturing , although that can save costs, but will bring endless troubles ." Professor, China University of Petroleum , China Academy of Engineering in 2012 Shen honest outcry International Petroleum industry Forum held recently .   With the rise of shale gas in the world , the development process is also used in the maide hydraulic fracturing method of rapid promotion , but the potential groundwater contamination and other environmental threats can not be underestimated . Previously, hydraulic fracturing has caused controversy in many countries , the French government issued a ban on its even .   For such a " recipe for disaster " technology , there is no proven technology can replace . However, according to the reporter , the world has begun to study the relevant alternative technologies , including some of China's research institutes.   It is reported that China University of Petroleum ( Beijing ) and China University of Petroleum ( East China ) After four years of research and experimentation , initially explore a supercritical carbon dioxide to develop unconventional oil and gas programs . Although the study is still in the laboratory stage, but for the alternative technology of maide hydraulic fracture stimulation ,the project leader Shen honest and told the " China Science News" reporter : "The future had to go this way ." Hydraulic fracturing controversy and more   The so-called hydraulic fracturing method refers to the chemical substance mixed with sand and high pressure water injection wells in parallel to break the shale and release shale gas. Every hydraulic breakers require millions of tons of water , and a large number of chemicals added to the fracturing fluid is injected though deep strata , without causing direct contamination of groundwater, but in the long run, there will still be a potential hazard.   In fact , hydraulic fracturing is not a new technology, already put forward in the 1940s , was mainly used in the transformation of old wells , enhanced oil recovery . According to Dean of China Langfang Development Research Institute of Petroleum Exploration Dingyun Hong , China's in the 1950s would hit the first saliva fracturing wells across the country each year there are 30,000 new wells.   For hypotonic ultra-low permeability oil , unconventional oil and gas reservoirs to increase production, the effect of hydraulic fracturing technology is obvious . But for such a shortage of large country , its fracturing process consumes a lot of water is quite amazing .   2011 China's first shale gas exploration in the Sichuan Weiyuan recovery , the British "Guardian" whether the region had adequate water resources has questioned , and that this will be the biggest challenge of shale gas development .   In addition, if shale gas development will lead to earthquakes and other issues , the U.S. Geological Survey is also under investigation , is not yet known .

Hydraulic fracturing

Hydraulic fracturing is a broad prospect for oil and gas well stimulation,  maide hydraulic fracturing method is the main form of exploitation of natural gas, requiring the incorporation of chemical substances with plenty of water poured into the hydraulically fracture shale to release natural gas. The technology in 10 years in the United States to promote a wide range, but the Americans are worried that the technology will pollute the water, thus threatening the local ecological environment and the health of residents. And that the technology to bring great harm to the environment, including water so spontaneous combustion, causing a small earthquake. Opponents point out the potential environmental impacts, including contamination of groundwater, freshwater depletion, air quality risks, gases and hydraulic fracturing chemicals to migrate to the surface, the surface leakage and backflow contamination, as well as the impact of these issues on health

Single well stimulation effects of hydraulic fracturing and its effects prediction

From the point of view of reservoir engineering , hydraulic fracture is hypertonic with oil layer with a certain directional length, width and height of the geometry. After single well fracturing, hydraulic fracture system consisting of the wellbore , and reservoir connectivity when the area is much larger than the area of ​​the wellbore without maide hydraulic fracturing significantly reduces the time of the formation of a single well production flow resistance , which is after fracturing a single the basic mechanism of increasing production wells. When the drilled reservoir, near the bottom zone due to drilling and other injuries leaving decline, so that by fracturing  maide Hydraulic  fracture through the injury zone ( generally hurt with less than 2m) into uninjured reservoir, so that did not hurt the oil layer the oil flow through hydraulic fractures into the wellbore , restore and enhance the natural capacity of the well . When single well fracturing, often both mechanisms work.
In general, the relatively high permeability reservoir, due to the pressure of the production wells into production soon entered the quasi-steady flow conditions , the output can be used to predict the radial flow equation solving , generally , it can be used with McGuire and Sikora Prats way to solve it. Conversely , in the relatively low permeability reservoir , production well pressure operation, the liquid oil will long remain unsteady flow conditions , the impact of the crack should be solved in a non- steady-state conditions , can be applied to non- steady typical curves plates or single-phase reservoir simulation flow Agarwal et al state or Holditch et al . If the water in the reservoir and for the overall development of fracturing its production forecast dimensional numerical simulation of three-phase reservoir need to use . Using models and calculation methods yield the correct pressure , is the basis for economic optimization of fracture design .

Fracturing sand blocking mechanism and prevention technologies

Water is an important american sand fracturing stimulation of low permeability gas field, due to the high angle directional well completion, perforation orientation is inconsistent with thin decision to stress, fracturing layers crack direction, multi-layer structure interaction, make fractured wells week initial bending cracks and multiple fractures, blocking the formation fracturing sand. The results confirmed: the formation of the main factors is well maide fracturing sand plug multiple fractures week bend limiting fracturing fluid flow in fractures; overlapping multi-slit width of cracks caused by competition proppant bridging; natural fractures or multiple fractures to reduce fluid loss efficiency of the fracturing fluid, affecting the development of the main crack. Prevent fracturing sand plug on drilling vertical wells drilled as possible to improve the perforation phase, the application of the same diameter of the pump stops proppant slug technology to promote the main crack extension, to ensure adequate fracture width, prevent fracturing sand plug.

There are many kinds of fracturing fluid composition

As the case may be, the main purpose is to look at its
Packer fluid is divided into two types: the first water as a dispersion medium such as water-based  maide fracturing Proppants thickened water, gel, oil in water emulsions, water-based foam and so on are some of the acidic solution. The second is mineral oil as a dispersion medium such as

oil-based  maide resin coated frac sand fluid thickened oil, oil-in-water emulsion, oil-based foam.
Fracturing fluid performance requirements: good high viscosity, lubricity is good, a small amount of fluid loss, low friction, to be fracturing fluid layer without clogging and damage, fluid mine pollution, thermal stability and shear stability , low residue, good compatibility, broken plastic rapid, wide supply, ease of preparation, economical and reasonable.

Fracking strengths and weaknesses

We have long been considered a non- gelled water is one of the most cleanest, most economical fracturing fluid . If the filtration problems in the formation fracturing fluid compatibility issues and minimal case , the non- thickened water as a base maide fracturing proppant fluid will be of great significance . These stimulation usually refers to  maide hydraulic fracturing proppant,reducing water resistance or branches fracturing fracturing ( occasionally ) , they usually require a large number of high-speed pumped water containing a small amount of reducing agent and proppant . In the application, compared with the traditional thickening fluid , this method can reduce the capital investment on the one hand , on the other hand so that hydraulic fracturing is more economically viable than other uses thickening fluid fracturing methods. Like other technical measures to increase production and hydraulic fracturing has its advantages , but also has its drawbacks . This particular method is the key to its screening principles will be applied to fit the unique advantages of this region or strata .
1 hydraulic fracturing potential advantages include:
2 simple operation, the use of a single chemical agents ;
3 can produce a considerable length of hydraulic ;
4 initial production can be compared with the normal stimulation intended ;
5 . Costs lower than normal stimulation .
As expected, the hydraulic fracturing also has shortcomings, such as :
1 confined to the low amount of sand strata ;
2 rapid sand filtration rate ;
(3) the effective fracture length is shorter ;
4 Compared with ordinary fracturing operations of similar size , the larger the decrease in final yield ;
5 The following fracturing aquifer has certain risks.
In essence , the hydraulic fracturing of various unfavorable factors show poor ability to carry proppant fracturing fluid . If the proppant can be effectively carried in place of water , the potential adverse consequences will be significantly reduced or even disappear completely .

Hydraulic fracturing

Maide Hydraulic Fracturing Proppants is increase production of oil and gas wells, injection wells by injection of an important technical measures, not only widely used in low osmotic pressure reservoir, and in hypertonic reservoir stimulation transformation also achieved good results . It is the use of advanced ground pump maide hydraulic fracturing benifits, high mucus has greatly exceeded the absorption capacity of the underlying displacement injection wells, in the bottom suffocating pressure, when the pressure is greater than the near wellbore formation rock to stress and tensile strength, in the bottom formation near the cracks. Continue with injected fluid carrying sand proppant, fracture extends forward and filled with proppant in the fracture closure shut the proppant to form a certain geometry and conductivity of sand filling in the vicinity of the bottom strata cracks that reach well stimulation process measures attention.