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2022-07-26
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[workshop] construction of horizontal directional drilling in hard rock - mountain crossing of product oil transmission pipeline

[workshop] construction of horizontal directional drilling in hard rock - mountain crossing of product oil transmission pipeline with high barrel temperature

China engineering machinery information

project overview

the project adopts horizontal directional drilling technology to lay product oil transmission pipeline through the mountain, with one hole and two pipes, and the pipe diameters are respectively Φ 330mm、 Φ 115mm。 The horizontal distance of the crossing section is 280m, and the crossing is carried out along the adjacent highway

model selected according to local conditions

geological information: the construction site is located in the low mountain and hilly area of eastern Guangdong, and the rock type is mainly granite, with high hardness. According to the geological exploration data, the crossing strata are sandy clay, completely weathered granite, strongly weathered granite and moderately weathered granite from top to bottom. The maximum uniaxial saturated compressive strength of moderately weathered granite in this area can reach 53.5mpa

model selection: XCMG xz400 can meet the construction requirements according to the pipeline specification, formation conditions, construction distance and other factors. For hard rock formations, in order to ensure the construction efficiency of guided drilling, xz400 drilling rig needs to be equipped with an additional 600l/min independent mud pump to drive the mud motor for rock guided drilling

the drilling tool is equipped with carbon nano dots (CDS) because of its high chemical stability, low toxicity, good biological compatibility and excellent photophysical properties

construction technology

guiding: first, use the ordinary inclined plate guiding bit to drill into hard rock; Then replace the mud motor and cone bit to drill through the hard rock section, and finally replace the ordinary inclined plate guide bit to drill until it is excavated

reaming: the reaming is carried out in five stages, and the final hole diameter is 600mm. The reaming sequence is 300mm, 400mm, 500mm and 550, which can be adjusted by mm and 600mm according to the model

back dragging: the pipe adopts roller carrier pad, and the drill pipes are connected in turn Φ 500mm cone reamer, transfer gear, bow shackle and pipe shall be pulled back

key problem

guided drilling tool "sinking": during construction, after the inclined plate guided drill bit penetrates the sandy clay and completely weathered granite stratum, it is necessary to replace the mud motor and cone bit, and plan to advance along the original drilling path. However, due to the low bearing capacity of the sandy clay stratum, the cone bit is easy to cut the lower hole wall when rotating in the formed drilling hole, resulting in the "sinking" phenomenon, Deviate from the original hole track

treatment measures: small diameter steel casing is used to isolate the soft stratum. In the original drilling without casing isolation, the mud pump volume is reduced to reduce the rotation speed of the cone bit, so as to reduce the disturbance to the hole wall and prevent drilling new holes

construction efficiency

through on-site tracking and observation for a period of time, the guiding construction efficiency of xz4 static load tensile testing machine system 00 in various strata is as follows:

case summary

during hard rock guiding construction, high-power mud pump is required to provide power for mud motor, so as to achieve ideal construction efficiency

the deviation making efficiency of mud motor is low. When a 3M drill pipe is pushed, the deviation making angle is usually about 1 °. It is difficult to raise the drilling angle in soft soil stratum

the grading span of rock reaming for small tonnage drilling rig is recommended to be 100mm. When the hole diameter is large, the grading span of reaming should be appropriately reduced

during rock formation construction, the hole shall be cleaned in time to ensure smooth drilling and prevent sticking

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