A Method for Determination of Safety Period of Extended Reach Well Considering Rock Fatigue Strength
A measurement method, extended-reach well technology, applied in strength characteristics, testing material strength by applying repeated force/pulsation force, testing material strength by applying stable tension/pressure, etc. Problems such as long displacement drilling cycle
Active Publication Date: 2022-05-24
CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD +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, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.
[0039] like figure 1 As shown, the method for calculating the safety period of an extended-reach well considering the fatigue strength of rock provided by the present invention includes the following steps:
[0040] 1) Obtain exploratory drilling cores in the target formation, process the cores into 12 (i.e. m=6) standard rock samples with an indoor standard coring cylinder, saturate the simulated formation water after numbering, and measure the actual diameter, length, Density and other physical parameters.
[0041] 2) Perform uniaxial compressive strength test and triaxial compressive strength test on No. 1 and No. 7 cores respectively, and obtain the uniaxial compressive strength UCS=40MPa, and the triaxial compressive s...
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Abstract
The invention discloses a method for measuring the safety period of an extended-reach well considering the fatigue strength of rock. The determination method comprises the following steps: 1) obtaining the drilling core of the target formation and processing it into a standard rock sample; 2) performing a uniaxial / triaxial compressive strength test on two cores; 3) performing a constant load strength test on the remaining cores, Record the failure cycle and establish the functional relationship; 4) Calculate the uniaxial / triaxial compressive strength under the regularized cycle; 5) Calculate the internal friction angle and cohesion value, and establish their functional relationship with time. 6) Calculate the change law of collapse pressure with time in different azimuths of extended-reach wells. The present invention is based on the indoor rock fatigue strength testing experiment, by obtaining the decay law of the uniaxial / triaxial compressive strength of the rock with time under a fixed load, and further calculating the strength parameters—internal friction angle and cohesion force with time, and finally obtaining The change law of wellbore collapse pressure with time, that is, the safe drilling period.
Description
technical field [0001] The invention relates to a method for determining the safety period of an extended-reach well considering the fatigue strength of rocks, and belongs to the field of drilling and completion of petroleum engineering. Background technique [0002] Extended-reach drilling technology can cost-effectively explore and develop oil and gas fields in offshore, coastal, islands and areas with harsh ground conditions, reduce the construction of platforms, artificial islands and the number of oil and gas wells drilled. For old oil and gas fields, the original infrastructure can be used to drill extended-reach wells, accelerate the exploration and development of the oilfield, shorten the oil production cycle, expand the oil drainage radius, increase the production of a single well and increase the life of the well, and increase the production and final output of the entire oilfield. Recovery rate, significant investment savings. [0003] However, the extended-reach...
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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 CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD