Testing Applications


 

Testing Applications Related Terms

Testing Applications, DFIT, Frac Monitoring, Surface Pressure Transient Testing

Determining essential properties and assessing condition from surface measurements.  Primary applications...

Surface Pressure Transient Testing

The Surface Pressure Transient Testing (SPTT) technology is used primarily for self-unloading gas, wet gas, or gas condensate producers.


Mini-Frac, DFIT, MFO (unconventional)

Mini-Frac / DFIT / MFO tests are done for pre-frac, injection fall-off in low permeability reservoirs and provide data to determine ISIP, closure pressure, and net pressure, as well as identify leak-off type.  Through these tests, reservoir pressure and reservoir flow capacity (kh/µ) can also be calculated though ACA (pseudoradial flow).


Frac Interference Monitoring

As operators continue to downspace in unconventional plays, communication between wells is a reality and a significant event that many operators want to have knowledge of and an option to manage on a frac stage by frac stage basis.  This data gives operators a better understanding the well spacing needed for future drills as well as the impact of interference,  aiding development models that serve to illustrate these communication pathways.

Discussions with a reservoir engineer handling developed shale assets indicated his belief that significant value can be gleaned from capturing this data for later use during the production/depletion phase.  His specific comments were: “I wish we would have captured more of this data during the completion process to better help us troubleshoot eventual production/interference issues that arose”.

Our rental system allows for wireless collection of pressure data from multiple points to the frac site where options are available to view it real time or collect it for later use.  This system utilizes radio frequemcy signals and works within a mile radius assuming “line of sight”.  There are also options to capture data remotely via cell and satellite connections.

Pressure Build-Up (PBU) / Drawdown (conventional)

Pressure Build-Up (PBU) is the most popular pressure transient test normally used in wells with permeabilities above 3 md. Typical deliverables for a pressure transient analysis of a PBU are skin, permeability, and reservoir pressure. The drawdown test follows the PBU and provides an effective comparison of calculations with the PBU while understanding bottomhole flowing pressures in order to minimize sandface drawdown.


Injection Fall-off (IFO) / Step Rate

Injector wells are a growing application.  Producers are being converted into injectors and new grass roots are being drilled.  Preemptive knowledge of skin, permeability, and pressure parameters of each reservoir phase promotes an understanding of the effects of skin accretion which allows efficient and effective development of treatment schedules or re-visiting the composition and chemistry of the fluids being pushed downhole. If the well to be tested can hold a full column of water, without going on a vacuum, it is a candidate for surface measurement testing as opposed to running equipment downhole.


Converting Historically Acquired Surface or DH Pressure to Mid-Completion Depth

For many of our customers we have converted and analyzed surface pressure data acquired from SCADA or other surface pressure gauges.  Additionally, PetraCat processes and analyzes pressure data from subsea wells in events, such as Permanent Downhole Gauge (PDG) failure, where data from the subsea tree is used to convert to mid-perforations analyses.  Because PDG's are normally positioned thousands of feet above the reservoir there can often be significant discrepancies or thermal/fluid effects in the data sets.  The ability to build a thermal wellbore model utilizing both wellbore pressure and downhole gauge data, then "tune" it for PVT and DeltaP frictional losses, provides for you the opportunity to bring those surface or downhole pressures to your needed mid-completion depths.


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