PetroStreet

What are the best practices when complying to ISO 9001 and then to move to ISO 29001 designed for Oil & Gas industry?
We are considering this transition, any guidelines would be beneficial.

There are supplementary requirements over and above ISO9001 to come on-board with ISO29001.
Would strongly recommend you to start with a gap analysis of your current practices versus these supplementary requirements of ISO29001.
Once you identify those, then only formulize a plan to implement what is missing.
API actually has instituted these requirements especially for oil & gas industry and compliance to them upfront is a good idea.

See ideally, you must be focusing on the gaps within the following when obtaining ISO 29001 certification:

Supplier monitoring / vendor quality assurance
Risk management integration
Competency demonstration
Design change management
Traceability and calibration controls
Formal RCA and corrective action effectiveness
Structured NCR workflows
Interface management between departments
Inspection Test Plans (ITPs) maturity
Project quality planning

Addressing these early makes certification smoother.

Is it necessary that we opt for ISO29001 certification being in an oil & gas company?
Having ISO9001 itself should work all good?