1. The cycloid has an isochronal pendulum.

2. The oscillations were isochronal.

3. The long term strength has gotten from the isochronal curves.

4. Modified isochronal well test plays an important role in productivity evaluation of gas field.

5. Nowadays, the main method of determining oil and gas well deliverability is steady well test, that is back-pressure testing, isochronal testing, revisionary isochron test and single-point test.

6. According to this problem, this paper proposes a modified isochronal well test with hole liquid loading.