Mining Drilling Equipment
Asean/Thailand
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Factors affecting mining DTH drill speed
1) sedimentary stratum s far, stratum Mining Drilling Equipment with high hardness, heterogeneity, part of the interval high abrasive.
Thickness in the artesian well above 500 m group, mud shale, sandstone layer, sand mudstone density, hardness, formation, reach for mudstone quartz sandstone, siliceous cementation, rock hardness grade 7; Permian series of strata rock can be mining where the DTH bit level value of 4.7 ~ 7.5, change is big, hard and soft rock with high confining pressure effect, Permian limestone Triassic more than three times higher hardness, and the central belt of flint tuberculosis, coal and pyrite.
2) borehole instability. In the upper portion of the high and steep structure well shaxi temple group rushed a pearl formation (well depth 0 ~ 2500 m), lithology is mainly sand, clay, shale interbed. Due to strong water sensitivity and stress of the high and steep structure combination, make the borehole instability easily, borehole wall collapse. Collapsed in order to balance and improve the mining DTH drilling completion fluid density, DTH rock drilling tools drill speed greatly reduce lead to mechanical mining, such as day east 26 Wells in shaxi temple, artesian well group stratum mining DTH drilling borehole mining DTH drilling completion fluid density up to 1.35 ~ 1.63 g/cm3, produced by the high fluid column pressure of the pressure holding effect "to make mechanical mining DTH bit downhill to 0.96 m/h. Permian longtan, liangshan group is easy to collapse.
3) large stratigraphic dip, dip 8 ~ 55 °, up to 85 °, prone to the formation natural deflecting.
In order to control hole deviation often light pressure easing the bit in measures, thus greatly reduces the excavation speed of DTH drill Wells.
4) complex formation pressure system, mutual crisscross, from the negative pressure to the abnormal high pressure system with vertical pressure on the diversity of relative independence and lateral pressure on the system.
Carbonate gas reservoirs are fractured, porosity and fracture porosity 3 kinds of reservoir. Pore aerosols hidden pressure regularity is clear, basic performance for atmospheric pressure, can achieve balance mining DTH drill Wells, such mining dth bit as the east sichuan carboniferous, changxing reefs, etc. Aerosols and crack layer pressure depends on the strength of the geological movement regularity, and the strength of the rock itself is bad, it is difficult to predict. Mining DTH drill Wells in the presence of cracks and use high density, DTH drilling completion fluid used DTH drill into. Lead to a balanced DTH drill speed affect the mechanical mining, but mining DTH drilling completion fluid with low density DTH bit fast strong mining, encountered some blowout fracture risk is very big. Group, the changxing group where the two high pressure reservoir, owing to the high pressure gradient and rock hardness, and deep formation depth, excavation DTH drilling completion fluid density is 1.50 g/cm3 usually; The highest pressure gradient (YunAn 6 Wells up to 2.45 MPa/hm, mining DTH drilling completion fluid density of 2.41 g/cm3), the mining DTH bit rate hovered around 1.00 m/h for a long time. |
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