Method for measuring safety period of extended reach well by considering fatigue strength of rock
A determination method and technology for extended-reach wells, which are applied in the directions of strength characteristics, testing material strength by applying repetitive force/pulse force, testing material strength by applying stable tension/pressure, etc. Problems such as long exposure time of wellbore
Active Publication Date: 2021-09-17
CNOOC TIANJIN BRANCH +1
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Problems solved by technology
[0003] However, the extended-reach drilling cycle is long, and the formation and wellbore are exposed for a long time. How to accurately obtain the safety period of the borehole wall (that is, the collapse period) of the extended-reach well section and determine a reasonable drilling fluid density to support the borehole wall so that it does not collapse is a big problem. A key step in the successful implementation of displacement drilling
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[0037] The experimental methods used in the following examples are conventional methods unless otherwise specified.
[0038] The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.
[0039] Such as figure 1 As shown, the extended-reach well safety period calculation method considering rock fatigue strength provided by the present invention comprises the following steps:
[0040] 1) Obtain the drilling cores of exploration wells in the target formation, process the cores into 12 standard rock samples (i.e. m=6) with the indoor standard coring barrel, and saturate the simulated formation water after numbering, and measure the actual diameter, length, Density and other physical parameters.
[0041] 2) Carry out uniaxial compressive strength test and triaxial compressive strength test respectively on No. 1 and No. 7 rock cores, and obtain uniaxial compressive strength UCS=40MPa, and triaxial compressive streng...
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The invention discloses a method for measuring the safety period of an extended reach well by considering the fatigue strength of rock. The measuring method comprises the following steps of 1) obtaining a drilling core of a target stratum and processing the drilling core into a standard rock sample, 2) carrying out uniaxial / triaxial compressive strength test on the two rock cores, 3) carrying out constant load strength test on the residual rock core, recording a failure period, and establishing a function relationship, 4) calculating uniaxial / triaxial compressive strength under a regularization period, 5) calculating an internal friction angle and a cohesive force value, and establishing a function relationship with time, and 6) calculating the change rule of the collapse pressure of the extended reach well in different directions along with time. On the basis of an indoor rock fatigue strength test experiment, the attenuation rule of rock uniaxial / triaxial compressive strength along with time under a fixed load is obtained, the change rule of strength parameters-internal friction angle and cohesive force along with time is further calculated, and finally the change rule of borehole wall collapse pressure along with time is obtained, namely the safe drilling period.
Description
technical field [0001] The invention relates to a method for measuring the safety period of an extended-reach well considering the fatigue strength of rock, and belongs to the field of drilling and completion of petroleum engineering. Background technique [0002] Extended reach drilling technology can economically and effectively explore and develop oil and gas fields in offshore, coastal, islands and areas with harsh ground conditions, reducing the number of construction platforms, artificial islands and drilling oil and gas wells. For old oil and gas fields, the original infrastructure can be used to drill extended-reach wells, accelerate oil field exploration and development, shorten oil production cycle, expand oil drainage radius, increase single well production and extend well life, increase the production of the entire oil field and ultimately Recovery rate, greatly saving investment. [0003] However, the extended-reach drilling cycle is long, and the formation and...
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Login to View More IPC IPC(8): G01N3/32G01N3/08
CPCG01N3/32G01N3/08G01N2203/0003G01N2203/0005G01N2203/0019G01N2203/0073G01N2203/0252G01N2203/0256
Inventor 袁俊亮范白涛李中幸雪松谢仁军何英明周长所徐国贤
Owner CNOOC TIANJIN BRANCH