| 摘要 |
The present invention discloses a process and apparatus for treating a wellbore, comprising subjecting a substantially same portion of the wellbore to vibratory waves produced by a plurality of vibratory wave generators. The vibratory waves may have about the same frequency or a plurality of frequencies, and the frequencies may partially overlap, not overlap, or be modulated across a range. Additionally, the frequencies may be modulated in an oval, hoop, and flexural modes. The vibratory waves may be produced by firing the vibratory wave generators simultaneously or in sequence. Preferably, the vibratory waves are acoustically streamed in a viscous boundary layer near obstacles, outside a viscous boundary layer near obstacles, or in a free non-uniform sound field. In a preferred embodiment, a vibrating pipe and a piston pulser are used as vibratory wave generators. In another preferred embodiment, a vibrating pipe, piston pulser, and a valve are used as vibratory wave generators. In another preferred embodiment, the thickness and change of thickness of a mudcake on the interior surface of a wellbore are measured to evaluate the effectiveness of the wellbore treatment. The speed of sound in the wellbore fluid is calculated. An ultrasonic signal is transmitted from a transducer, and the time of flight for an echo of the ultrasonic signal reflected from the boundary of the wellbore fluid and the mud cake back to the transducer is measured. The time of flight for an echo of the ultrasonic signal reflected from the boundary of the mud cake and the interior surface of the wellbore back to the transducer is also measured. The thickness of the mudcake is calculated according to the equation L=(T2-T1)*c/2, where L is the thickness of the mudcake, c is the speed of sound in the wellbore fluid, T1 is the time of flight for an echo reflected from the boundary of the wellbore fluid and the mudcake, and T2 is time of flight for an echo reflected from the boundary of the mudcake and the interior surface of the wellbore. The change in thickness of the mudcake between a second point in time after a first point in time is calculated according to the equation DELTAL=0.5*(T1a*ca-T1b*cb), where DELTAL is the change in thickness of the mudcake, ca is the speed of sound in a wellbore fluid at the second point in time, cb is the speed of sound in the wellbore fluid at the first point in time, T1a is the time of flight for an echo reflected from the boundary of the wellbore fluid and the mudcake measured at the second point in time, and T1b is the time of flight for an echo reflected from the boundary of the wellbore fluid and the mudcake measured at the first point in time.
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