Horizontal wells in tight reservoirs staged fracturing technology status and progress

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Abstract

In recent years, with the oil and gas resources continue to make breakthroughs in key technologies, unconventional oil and gas resources in the industry and the market began to be sought. The US shale gas development has received periodic progress, and the tight gas also entered into a stage of rapid development. The tight oil and gas resources have wider distribution, reserves abundant, with the sub-horizontal well fracturing technology matures and widely used, it becomes possible for the dense oil and gas resources in the future to enter large-scale industrial development and utilization.

1. The overview of tight gas and stages fracturing of horizontal wells technology

Tight oil and gas is an unconventional oil and gas resources, the presence of a dense layer of the main source rock ode internal mezzanine and close source rock, and has a low density, large reserves of oil and gas well conditions and other characteristics, is the second after another large shale gas exploration hotspot fields. West unconventional energy development time earlier, mainly because from the 70s of last century, in the midst of a long-term energy crisis in the United States, for example, for global strategic considerations, the United States policy on the policy of tight gas reservoirs exploration and development to give a strong support to the exploration and development of unconventional oil and gas resources to get a lot of progress, the United States is currently the county’s most successful exploitation of tight oil, its success in this regards become more and more popular in the worldwide.

Tight oil and shale gas development approach is quite similar, all must be applied to the horizontal well fracturing technology, which is the technical background of tight oil and gas has rapidly development following the shale gas. Currently, horizontal well fracturing technology has been a massive worldwide application of the technology of research and testing have made certain achievements, technological innovation capability is increasing, and many large domestic oil companies have been establish and horizontal well fracturing technology-related subjects technology system, but also in Daqing, Shengli, Tarim oilfield low permeability 13 block implementation of the “factory” mode of operation, which greatly reduces the density of oil and gas development operating costs.

2. The application situation and development trends of horizontal well fracturing technology

2.1 The application situation of horizontal well fracturing technology.

The application of horizontal well fracturing technology has become a reservoir to improve oil recovery, oil exploration and development of the overall efficiency of an important way, is a mechanical packer stages fracturing, horizontal jet stages fracturing it, limiting segmented pressure process characteristics and parameters cracl, liquid rubber plugs were stages fracturing technology in China.

First of all, mechanical packer staged fracturing technology

The technology is divided into double seal single staged fracturing pressure and sliding sleeve fracturing packer section. The former is mainly applied to the well casing, because of its simple string structure, ease of construction and easy to play out the string after construction, can be targeted staged fracturing. After construction, is completed, you can quickly flow back fluid wells to the ground and put into production, it is worth nothing that the use of the process must ensure that the sealing performance of the packer, the latter is mainly applied to horizontal wells cased-hole completions its column structure is relatively complex, mainly by hydraulic anchor packer, screen guide shoe, packer tee and pitching blasting open sleeve sleeve and pressure-composition, the process can be achieved using multistage pressure crack effect, the production string string and fracturing string is one, the construction efficiency is very high.

Secondly, the level jet staged fracturing technology.

The technology is divided into fixed string segmented hydraulic fracturing and coiled tubing segment jet spray water conservancy fracturing two processes, the former is the jet perforating and hydraulic fracturing technology into one, with a unique position of, in no the case of mechanical seals will be able to improve the speed and precision multi-fracturing of the process according to the Bernoulli equation can be pressure energy into kinetic energy, the naked eye can, screenless completion of horizontal wells and casing Inoue carried sand fracturing, higher construction safety, but also to combine with large diameter coiled tubing, more convenient construction, of course, the performance requirements of the fracturing fluid is relatively high; the latter is a new hierarchical fracturing process, not only to achieve large-scale transformation, but also to achieve a layered, fine fracturing purposes, the use of this technology can reduce cycle times, and more flexible tiered fine, dense reservoirs multistage transformation provides an effective The way the process is currently in foreign countries has been large-scale applications, the amount due to the impact of domestic coiled tubing equipment, and overall application size was small.

Third, multi-level horizontal wells can be drilled bridge plug staged fracturing technology.

By security fittings, guide shoe and drill bridging basic structure composed of multi-level segmentation drillable bridge plug fracturing string, the technology of the bridge plug, string and other requirements are high, such as the bridge plug must be sealed and reliable, corrosion temperature and pressure, the material can be drilled, and must be completed after the fracturing of the bridge plug at all levels of drilling and milling; after construction can not take control of the direct use as a production string, the next technology to optimize the response string. The technical advantages, can save time and operating costs and improve the efficiency of construction, and other related technologies to foreign oil services company Halliburton has been widely used in the world, China Oilfield Oil Institute and other units are also independent research and related technologies, practical application has also been affirmed.

Fourth, the liquid stopper staged fracturing technology.

The technology can replace the separator staged fracturing and other tools for fracturing oil shutoff layer, can effectively solve the casing deformation due to oil exploration, mine has a litter, etc. You can not use a mechanical packer for the construction of staged fracturing problem, present the technology in horizontal wells openhole completions process has been widely used to make up for the deficiencies which exist, and have controlled crosslinking time, broken plastic controllable time, temperature and pressure of the reservoir low damage , the process is simple, high security features, in our Daqing, North China Oil Field have been successfully applied, and this is the future direction of development points off the fracturing,

2.2 The technology trends of horizontal well fracturing

Horizontal well fracturing has now become the main direction of oil and gas reservoirs compact transformation, although the domestic application of the technology are still exist some problems, but with the continuous progress of the domestic related technologies, as well as the introduction of technology continues to digest, the degree of localization process of fracturing technology equipment will be increasingly high, the current combination of tight reservoir characteristics, some key technologies are in succession was broken, and the gap with foreign technology is gradually narrowing, continue to lower horizontal well technology and staged fracturing reservoir stimulation technology costs, the domestic large-scale application of the technology has made possible a wide range of dense oil and gas distribution, large reserves, huge development potential, staged fracturing of horizontal wells technology is very broad application prospects.Conclusion: China has huge unconventional oil and gas resources, with the large-scale application of US shale gas revolution wave of staged fracturing and horizontal well technology, dense oil and gas exploration and production has entered a new stage of development, dense low-cost oil and gas explorationIt has become a reality.

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