Fracture mining technology

Fracturing technology by injecting sand, water and chemicals into wells, the formation of cracks in the shale formation and extraction of natural gas. Due to the level of drilling technique, the changes in mining techniques for the development of non productive deep shale formations over the past ten years, conventional,unconventional natural gas and two other forms of (tight gas, CBM) along with the increase of 30%-40% of domestic energy production.

But some people think that the energy gain is costly, and France, the United States of New Jersey and New York, due to the environmental impact of worry, has banned takefracturing technology of hydraulic mining.

In the numerous of mining process view, there is a thought that this will pollute thegroundwater, caused by the earthquake, causing chemicals such as methane andbenzene leak into the air. So far, oil and gas regulators and other groundwater protection experts also found no sign that is directly linked to the China proppant and groundwater pollution, but also did not conduct a comprehensive research on this technology.

Civil and Environmental Engineering Department of University of Texas-Austinprofessor Danny Reible recently by virtue of its groundwater expertise in helping the U. S. environmental protection agency to study the Fracturing proppants , he thought that the occurrence of pollution may be due to poor drilling design and construction or waste management surface bad.

Method of limiting layer fracturing

To pressure for multilayer and each layer has different rupture pressure wells. Thenumber and diameter of control of each layer perforation, and as far as possible to improve the injection rate, using the first frac sand perforation friction layer improve the bottom hole pressure and achieve a divider multilayer purpose.

A, B and C three reservoir, fracturing pressure respectively 24, 20 and 22MPa,according to the respective eyelet perforation scheme launched. When injected into the bottom hole pressure is 20 MPa, B laminated open; and then enhance the displacement, due to perforation friction is proportional to the displacement, B layerperforation friction reached 2 MPa injected into the bottom hole pressure is 22 MPa,namely the C layer is pressed; continue to improve the displacement, B layerperforation friction reaches 4MPa at the bottom of the hole injection the pressure is 24 MPa, the A layer is pressed to open. Perforation of the effect is similar to thedownhole throttling device, with a Ceramic proppants displacement increase, the bottom hole pressurecontinues to improve, and then laminated open.

Limit the key flow method of layered fracturing perforating fracturing is to plan according to the requirements of reasonable design, including perforation, hole density and pore size, so that the completion and fracturing to form a unified whole.

Fracture Heightgrowth controlling technique

When the oil and gas layer is very thin or middle layer and the shielding layer between the minimum horizontal main pressure difference is small, the crack pressure height to easily enter the shielding layer, when the need to control the natural gas fracturing heightextension. Can be realized by controlling the Proppant fluid performance parameters and construction displacement, the more reliable is the artificial interlayer fracture Heightgrowth controlling technique.

The basic principle is in the pre adding liquid floating or sinking type guide agent,through the front fluid into the crack, floating guide agent and sink type guiding agentrespectively, floating and sinking gathered at the top and bottom of artificial fracture,low permeability formation compaction artificial barrier, prevent crack pressure upward/ downward propagation, reach the fracture height controlling purpose. In order to make the two guide agent can move up and down, usually in the injection with guiding agent liquid short-term after the pump stops, then the fracturing operation normal.

Artificial interlayer fracture height controlling technology is mainly used to 1) bulkhomogeneous formation production layer and non production layer interbed; 2)production layer and between layers of water gas, good interlayer; 3) production layer and the shielding layer stress difference can not effectively control the cracks ofvertical extension.

Fracturing fluid cost and environmentally friendly use of natural gas

Natural gas used for hydraulic fracturing is said to be in American breakthrough, shale gas has low cost, but the domestic cost but has not closed, what reason be? A bossinadvertently say one of the mysteries of. Fracturing fluid is the main cost of shale gasis said to account for more than 70%, and the main component in the shale gas fluidssuch as sodium salicylate and quaternary ammonium salt, sodium salicylate salicylic acid if not made of raw materials or without high level such as pharmaceutical grade,the intermediate process of sodium salicylate as raw material for the production of salicylic acid in phenol water crude sodium salicylate the solution of sodium salicylate,take this cost can be greatly reduced by at least half or even below 40%, however at the cost of the crude sodium salicylate containing 2-3% phenol toxicity great. Thisleads to two problems, one is USA really with crude sodium salicylate as fracturing fluid (maybe it can oppose shale gas from USA environmentalists and proposed the pollution of fracturing fluid containing phenolic evidence), this can be from the exportstatistics or manufacturers such as the biggest foreign trade personnel than domestic manufacturers to understand, two is the 2-3% of phenol will be diluted to what extentas to whether the trace phenol also has the role of sterilization effect of 2-3% relative to the groundwater quality can be ignored or even play a positive role in the pollution of water resources, the domestic serious groundwater pollution serious situationdecision is difficult. So, the oil well fracking fluid cost can be greatly decreased by more than half, the key is to consider the influence of environmental protection.

By ceramic shape classification

Ceramic according to shape into gravel-type ceramic, spherical and cylindrical ceramic ceramic.
(1) gravel-shaped ceramic
Gravel-type ceramic Hydraulic Fracturing Proppants use natural mineral production, the first stone grinding, roasting, and then sifting; also available in natural and artificial light materials such as pumice, scoria, cinder, coal and other natural or calcined directly broken screen points derived.
(2) spherical ceramic
Spherical ceramic fracturing proppants is the use of the disc pelletizer. First raw flour, then add water pelletized into balls and then baking or curing together. At present, China's ceramic Most of this variety.
(3) a cylindrical ceramic
Cylindrical ceramic commonly used plastic extrusion. First made of mud, and then cut into a cylindrical shape. This ceramic is suitable for high plasticity clay like material, the yield is relatively low. If using a cylindrical blank brick back firing in the kiln cylinder roll into an oval shape.

Technical construction of oil proppant production safety and quality requirements

Petroleum proppant for clothes, skin corrosion strong, with liquid, must pay attention to safety during construction.
(1) pay attention to the preparation of oil proppant Wear PPE, bold but cautious, there is someone in charge of directing with liquid and well in advance of each lotion, once splashed acid in the body, the face you want to rinse with water, heavy timely sent to hospital for treatment.
(2) with a good oil proppant placed after the ferry to check the acid tanker valves, liquid inlet lid is on tight, can not have drip, drain phenomenon. Vehicle shall be marked with the danger mark at the wellsite shipped cracks pay attention to safety.
(3) the construction team on well after construction should be carefully checked before the wellhead valves are complete, whether the screws tightened to the construction until after passing the wellhead. Firstly wellhead natural gas fracking test the pipeline construction, leak-free mayonnaise, the only sour note to the well.
(4) When a large amount of acid, when a new well acidizing process to prepare the production command vehicle, ambulance wells.
(5) in strict accordance with the design and construction. The quality of acidizing is directly related to the post-acid effect. Therefore, we must ensure construction quality.
① conduct tests, before acidizing, a clear division of labor, unified command: Non-staff shall enter the high-fracking process zone.
② strict accordance with design requirements, acidizing.
③ guarantee the construction of the oil leak proppant not AIDS, given the amount of fluid play enough design.
④ for matrix acidizing pump pressure must not exceed the fracture pressure, ready to observe the construction of pump pressure, ranked the most changes.
⑤ take full, take prospective construction pressure, displacement, construction time, etc., well carefully recorded.
Late Management (four) Construction
After acidizing oil and gas wells, bad management, construction related to the effect of acidification. After acidizing wells shut as designed after timely open wells. If self-spray nozzle is installed drainage capacity requirements; generally when dropped O.1% residual acid concentrations, flowing well stop production of crude oil, non-flowing well from a string acidified turn pump pumping into production. Not since the spray is necessary and timely rehearsal is the key to prevent secondary precipitation acidification success. Oil and gas wells in the production process should be carefully recorded oil, casing fracturing fluid , daily production of oil and gas and other data, such as the timing of the measured fluid level wells. With drainage conditions on injection wells after acidizing according to design requirements to drain residual acid, restore water when the residual acid dropped when OI%; do not have drainage conditions, timely recovery water injection wells, the residual acid formation squeeze Deep. Carefully recorded during the injection pump fracturing proppant , casing pressure, oil fracturing sand , water injection daily, injected water quality data, timing measurements indicate absorption curve, the injection profile and so on.After acidification with a note for a smooth construction by water injection rate can not be too large, otherwise easily lead to the formation velocity sensitivity, acidification effect: To inject water quality water quality standard character sets, this plug formation injection wells, acidified to fail.

Natural gas fracturing transformation project success

Research high temperature fracturing fluid system for high temperature, low permeability reservoir damage sensitivity by low damage, low residue carboxymethyl guar gum study, the formation of high temperature and pressure applied to Jilin Oilfield low permeability tight gas reservoirs of low pressure damage fracturing fluid system, heat index reached 180 degrees, effectively reducing the fracturing fluid injury rate for natural gas wells effective development has provided a guarantee; the second is to carry out research to reduce the system pressure fracturing technology for deeply buried reservoirs, high stresses characteristics, by fracturing string optimization, reducing friction fracturing fluid technology bauxite proppant research, forming a lower fracturing fracturing system supporting technology, to provide technical support for the high-pressure fracturing wells, construction of pump fracturing equipment to improve efficiency, reduce fracturing difficulty; third, to conduct wear thin interbedded sandstone and mudstone layer fracturing technology for over sand mudstone, by building a reservoir model for reservoir analysis, optimization fracturing parameters, forming a thin interbedded wear layer fracturing technology, effectively increasing the use of a single well surrounding reserves; four is to carry out a large-scale study of fracturing technology for low permeability fractured ceramic ball tight gas reservoirs massive demand, by fracturing wellbore integrity analysis, ground systems for liquid build, remote control and command system decision supporting the formation of large-scale fracturing technology to provide effective technical support to improve the well production, increase single well controlled reserves. To provide effective technical support for the effective increase well production, increase single well controlled reserves.