In upstream oil and gas it is mandatory as per the regulatory requirements and it is a good practice to regularly test every oil well. The welltest results are used by many parties for various reasons. In an ideal world the oil welltest results are close to the results of the models built by development staff.
A great article by Vincent B, an expert in oil and gas production maximisation, oil well testing and production data quality, and consultant with Consult 2050.
The benefits of Top Quartile (TQ) performance in welltesting are:
- Welltest results can be trusted and can be used to take high quality business decisions
- Little to no time wasted by field staff to generate good quality well test
- Little to no time wasted by development to build well and nodal models
- Good cooperation and mutual respect between operations and development
Overall the TQ performance in welltesting is an enabler for TQ performance in production optimization thru well reservoir and facility management both in terms of production and in terms of cost. Unfortunately, the current reality is much different in many oil companies. Development staff often struggle with the welltest results and hence do not trust the welltest data. Bad or sub optimal welltest results has become an accepted problem. As a consequence, Development staff built their well and surface models on their own data. This is like working in the dark depending on the quality of the data at hand. Within operations a lot of time is wasted due to bad well test results.
How best to overcome this undesirable situation and work towards TQ performance in routine welltesting. The recommended way out is to appoint a technical expert and a sponsor. The sponsor should preferably be a member of the Operations Leadership team. Below are the proposed roles for these 2 individuals.
Technical expert is expected to:
- Act as the most knowledgeable person in the company
- Create and maintain roles and responsibilities for the relevant parties (operator, operations supervisor, person who validates the welltest result, person who determines welltest duration, person who determines purge time, etc.)
- Provide training to relevant parties
- Create and maintain an overview for each welltest separator / multiphase welltest meter what is required to obtain reliable and welltest results
- Create a gap analysis for each test separator /multiphase welltest meter of what is currently in place versus overview what is required
- Create and maintain an action plan for each welltest separator / multiphase welltest meter including action owners and due dates
- Provide operations input in projects with respect to well testing
Sponsor is expected to:
- Appoint the technical expert
- Ensure that the technical expert can spend part of his/her time on routine welltesting
- Support the technical expert in removing blockers (if any)
- Review findings, action plans and progress
Assuming a sponsor supports the above, the first challenge for the sponsor is to look for a person who can develop into the technical expert role. At this stage the sponsor should consider to find a recognized professional from outside. That person is expected to work side by side with the appointed technical expert to speed up his/her development. This also means the sponsor can expect more progress and results in a shorter timeframe.
I have been fortunate that I was able to spent considerable time to improve welltest results in Oman, Syria, Nigeria and in the Netherlands. I have seen many different set-ups for welltesting and I can therefore pinpoint what is not right. I can assist to build a gap analysis and assist to build the action plan.
I have seen some bad experiences:
- Oversized rental compressor was installed to reduce flaring. The compressor was oversized because there were leaking test header valves and because there was no flare meter. The leaking valves inflated the welltest results in terms of produced gas.
- Gaslift metering not being maintained and not being used.
- The justification of a sizeable development project that was partly based on welltest results of a pilot. It appeared the welltest separator in the pilot project was not fit for purpose. Instead the welltest results were estimated and being reported as thrust worthy. The welltest results could not be validated because there was no working export meter.
Some tangible achievements:
- In one OpCo, development had justified spending million USD’s on replacing 3 welltest pipe separators. Instead, I used the available raw PI data to demonstrate how these meters work. Subsequently the effort was put in to re-commission the existing meters. This was done satisfactorily and at very low cost.
- In the Netherlands I recently worked on a gaslifted onshore oilfield. This resulted in a long list of improvements. The only thing that costed some money was the replacement of the orifice plates of the gaslift meters to make sure all of these meters were in range.
- I justified why the agreed global IT project for welltest validation was overly complex. Instead I organized a small project to prove the proposed simple concept. The proposed concept was proven and hence the decision by the global LT not to pursue the agreed global IT project.