Is there is a chance of writing test cases in adhoc testing

you can create regression suite in QTP to do regression test every time before build will get deployed.

Adhoc testing is the least formal of all testing methods. Its better to make a documentation of what needs to be tested before performing adhoc testing. The documentation not necessarily be formal testcases. This would ensure mapping and documenting any possible errors that might arise during testing. Testing is driven by the needs of the system under test, not some document that will be changing repeatedly in the future.