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How to choose mud when diamond drill bit encounters geothermal water
Release time:
2018-06-07
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The normal drilling construction with diamond drill bit is usually done with clean water, because it can be used locally, without transportation, without cost, etc., by the majority of the captain as the first choice of flushing fluid. However, in many cases, it is still necessary to use mud to replace the water to flush the borehole, such as the situation containing geothermal water during the drilling process.
Usediamond drill bitNormal drilling construction is usually the use of clean water can be, because it can do local materials, no transportation, no cost, etc. by the majority of the captain as the first choice of flushing fluid. However, in many cases, it is still necessary to use mud to replace the water to flush the borehole, such as the situation containing geothermal water during the drilling process.
When drilling like hot spring wells, geothermal wells or drilling holes containing geothermal water, the water temperature at the bottom of the hole is often above 80 degrees Celsius, and the heat generated by the high-speed rotation of the diamond bit cannot be well taken away by the flushing fluid, resulting in the temperature of the diamond matrix at the bottom of the hole above 150 degrees Celsius. At this time, the selected flushing fluid should not only have the performance of the general drilling flushing fluid, but also, most importantly, the performance of the flushing fluid should withstand the influence of the temperature at the bottom of the hole. For medium and low temperature geothermal water, the general flushing fluid can meet the requirements, but for the high temperature of the bottom of the hole, the non-dispersed low solid polymer mud should be selected as the flushing fluid. The following gold drill bit factory will introduce the performance of non-dispersible low solid polymer mud, the ratio of common non-dispersible low solid polymer mud and the precautions for use.
Introduction of 1. non-dispersible low solid polymer mud
The so-called "non-dispersion" has two meanings: one means that the clay particles constituting the drilling fluid should be kept within the range of 1 ~ 30μm as far as possible, and should not develop in the direction of less than 1μm; the other means that the drilling cuttings mixed into the drilling fluid system are not easy to disperse and become fine. The so-called "low solid phase" means that the volume fraction of low-density solid phase (mainly refers to clay minerals) should be maintained to the lowest within the scope allowed by the drilling project. The following are the requirements for non-dispersible low solids polymer muds:
1. Solid content (mainly refers to low-density clay and drill cuttings, excluding weighting agents) should be maintained at 4% (volume) or less, which is approximately equivalent to a density of less than 1.06g/cm3. This is the core index, is the key to improve the drilling speed, should try to do.
2. The ratio of drill cuttings to bentonite shall not exceed 2:1. Practice has proved that, although the drilling fluid in the solid phase, the better, but if no bentonite, it can not establish the necessary properties of the drilling fluid, in particular, can not guarantee the necessary rheological properties of the hole, as well as the protection of the hole wall and reduce the aquifer pollution necessary to build the wall performance. Therefore, a certain amount of bentonite should be contained, and the lower the amount of bentonite, the better under the premise of ensuring the performance required for the establishment of the above drilling fluids. It is generally believed that it should not be less than 1%, and 1.3~1.5 is more appropriate.
3. The ratio of dynamic shear force (Pa) to plastic viscosity (MPa • s) is controlled at about 0.48. This is to meet the requirements of low return speed (such as 0.6 m/s) sand carrying, to ensure that the drilling fluid in the annular space to achieve flat laminar flow.
4. The dynamic shear force of non-weighted drilling fluid shall be maintained at 1.5~3.0Pa. Dynamic cutting force is the key parameter for drilling fluid to carry cuttings, in order to ensure good carrying capacity, the requirements of dynamic cutting force must be met first.
5. The fluid loss control shall be determined according to the specific circumstances. On the premise of stabilizing the hole wall, it can be relaxed appropriately to improve the drilling speed. Strict control should be exercised in strata prone to collapse. After entering the mining layer, it should also be strictly controlled to reduce pollution.
6. Optimize rheological parameters. If Carson mode is adopted, the ultimate high shear viscosity η ∞ = 3~6MPa • s,τ с = 0.5~3Pa;Im (shear dilution index) = 300~600.
7. Try not to use dispersant during the whole drilling process.
2. common non-dispersed low solid polymer mud ratio
There are many kinds of configuration proportions of common non-dispersed low-solid polymer mud, and there are many manufacturers. At present, the main proportions of such mud liquid on the market and their properties are as follows:
Precautions for the use of 3. non-dispersible low solid polymer mud
In addition to the mud performance of the reference table, the construction of the kilometer geothermal hole in the Central Plains area will be developed to high temperature with the geothermal hole. According to the needs of the drilling period, the rheological properties of the drilling fluid and other parameters will be controlled through the adjustment of the material formula to meet the strong wall protection and leakage stopping effect of the drilling fluid during the drilling period. However, when the drilling is conducted after the hole is formed, the viscosity of the drilling, the drilling fluid intruded into the drilling fluid and the drilling fluid will decrease and the volume will decrease, strength embrittlement, so that the underground fluid channel is smooth, the permeability of the formation is restored, and the production of production holes is increased. By selecting special compound biological enzyme preparation and corresponding chemical reagents, it is added to the polymer solution such as Na-CMC, guar gum and konjac. The biological enzyme preparation is used as a biocatalyst to control the degradation rate of polymers from long-chain macromolecules to short-chain small molecules. At the end of the drilling work, the polymer molecules change from long chain to short chain, and the viscosity of the drilling fluid automatically decreases in a human-controlled manner. As the viscosity of the drilling fluid decreases, the previously formed mud skin is automatically broken, the blockage in the pores of the production layer is eliminated, and the fluidity of the fluid is enhanced, so that the permeability of the formation around the hole can be restored, and the purpose of improving the production of geothermal water in the exploration hole and geothermal hole can be achieved.
At present, drilling mud can be said to be the cheapest drilling accessories, because of its low price and high efficiency, so many domestic customers, especially in the northwest region, use a large range. In spite of this, the gold drill diamond drill factory suggests that when there is no drilling with shrinkage and collapse, using clear water as flushing fluid is still the first choice. Mud flushing fluid requires rich experience due to concentration allocation. If the concentration is too high, diamond drill will increase wear.
Address of this article:http://www.ykzckj.com/
Key words:
Beneficial Mining Technology
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