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Testing After the Storm

By Anil Joy and Chris Floyd | Mon, 10 Nov 2008

Pressure transient testing is one of the cornerstones of well diagnostics.  Reservoir engineers utilize the data collected from their wells to make decisions that aid in extending the life of the field.  The main obstacle to pressure transient testing is the reluctance to shutting in a producing well.  However, in the Gulf of Mexico, shut-ins are frequently dictated by the arrival of hurricane season.  These mandated shut-ins provide the opportunity to acquire valuable reservoir data.

With the 2008 hurricane season past us, many wells are still shut-in due to platform and pipeline damage that occurred as a result of hurricanes.  With these extended storm shut-ins, operators in the Gulf used these shut-ins to obtain reservoir parameters for their wells.   One major GOM operator gathered static shut-in tubing pressures (SITP) by calling out SPIDR gauges prior to the re-opening of their wells.   DRC converted the SITP’s to bottomhole conditions and the results were used to satisfy the annual MMS (U.S. governmental entity) survey requirements.  This quick and simple test saved the operator time, money and production.

Other GOM operators utilized the extended shut-in and the SPIDR system to capture not only the SITP but also collect the subsequent drawdown or flowing test data.  The operators called out the units while the wells were still shut-in and had the SPIDR gauges recording when the wells were placed back online.  When they were ready to resume production, the well was opened at a constant choke.  By doing so, they were able to analyze for permeability and skin. 

One operator took full advantage of the mandated shut-in and performed an extended drawdown test when production resumed.   The extended drawdown consisted of 45 days of constant choke-size drawdown.  The extended drawdown enabled the operator to capture pressure transient data that DRC used to calculate permeability, skin and P*, but they were also able to utilize this post-hurricane drawdown as a reservoir limits test to determine the boundaries of the reservoir.  Acquisition of these critically important reservoir properties was made possible by an unscheduled and unwanted shut-in mandated by the hurricane. 

When the decision of shutting in production has been made for you, the many reasons for not testing have been remedied.  The remaining major issue encountered with this type of testing is the uncertainty of when the wells will be placed back in production.  To address this concern, DRC has developed a pipeline shut-in proposal. This proposal offers lee-way in the rental charges resulting from extended shut-in days due to pipeline start-up dates being delayed.

Along with storm mandated shut-ins, there are planned shut-ins for pipeline or facility work where the operator will have advance notice of both the shut-in and the start-up.  In either case, the use of the SPIDR system includes the benefits of having a DRC reservoir engineer aid in the specific test plan for your well.  DRC engineers are always available for free well test consultation and well test planning.  DRC routinely aids in optimizing well test procedures for their clients.  The SPIDR is delivered overnight in the U.S. and typically within 3 days internationally.