Operational Philosophy

A question came up today regarding the establishment of "operational philosophy" for new fields including rules for welltesting frequency (in addition to government requirements), well and reservoir monitoring, reservoir management, smart controls and automation, etc.  These are huge decisions for a field development team and it can be difficult to know where to start.  

Some suggestions:

a) By far the most valuable thing in the field are the reserves of oil and gas in the ground.  Look at their reservoir recovery processes. Ask if something were going wrong in the recovery of those reserves and you did not know it, what specific information would help you understand the problem and what would you have to control to correct the problem?  Repeat this for all the common things that can go wrong with your kind of reservoir given what you are certain about.  Then look hard at your reservoir uncertainties for other things that could go wrong.  There are many, many kinds of problems, but here are a few examples: If there were a thief zone taking most of the water injection and short-cutting across to the producer, how would you know this and how would you stop it?  If part of the reservoir has no water pressure support, how would you know this and how would you stop it?  Having the right information and controls--that is the key not only to running the field to recover the most reserves but to optimize the value of the field while it is producing.  Please don't make the mistake of designing your instrumentation and controls for only the 'base' case.


b) Regarding instrumentation and controls, go for redundancy.  If you want to see something sad, find a complex field with broken meters and gauges and chokes and talk to the team that is trying to optimize it.  They cannot trust anything and struggle to make the simplest of decisions.  Gauges and meters fail routinely.  What would you do if an instrument failed?  Could you use other information as a back-up?  Could you use other information to check a critical measurement?  For example, a subsea gas lift meter might fail (very often, apparently).  Can you use upstream and downstream pressures over a choke, or over a pipe section to give an indication of flow rate?  Could you use a second downhole pressure gauge to backup the first one if it failed?


c) A steady stream of the right data does cost time and money.  Even the best managers have to defend capital expenditures at all levels, so it is no good just to say "We need this extra meter."  Justifying the costs is straightforward using value of information concepts. To start, play out a scenario in the field reservoir simulation of things going wrong with no correction (because it is undetected) and the same simulation with things under control and look at he difference times the probability that this scenario might happen as the expected value of having this information.  For example, a waterflood with high voidage in one corner (because no one can measure SBHP there) vs the right voidage with extra downhole gauges.  Or a field with a poor (random) distribution of lift gas (because no one can meter the gas properly) vs the right one with spool sections and valves for easy installation of replacement/redundant meters.  These expected values will likely be much larger than the costs of measurements.  No one ever complained about a field where the data was too reliable and the controls worked all the time.


d) Make sure the gauges and meters that you get are themselves the most robust.  When you have a choice, go for meters with wide ranges of application, that can be field calibrated, can be easily replaced.  Sacrifice absolute accuracy to get robustness.  Often the person who is buying the meter will ask questions about the likely flowrates, gas to oil ratios and water cuts.  Don't give them single numbers.  Give them the full ranges of values that are possible.  For example, a single gas meter on a test separator sized for initial rates will be useless when the rates decline, or if the GOR is much lower than expected, or when the water cut climbs.  It might be very undersized when gas lift is used on the well.  And, give special consideration to gas lift measurements as they so often are poor (which is sad because dry gas should be the easiest to measure).  Gas lift gas to each well deserves accurate measurement because it will directly impact the optimum use of the lift gas, but also because the associated gas from each well will be very distorted with poor gas lift measurements, which result directly in poor operational decision-making and therefore lost recovery.


e) Make sure that the data that you measure can be collected and managed.  Data that is not readily available is effectively lost.  Look at the data and apply a 60 second rule: can I get this data on my desktop and start to use it in less than 60 seconds.   The longer it takes, the less likely staff is to make the effort to find out the truth and the more likely they are to make assumptions instead.