D51: Water Injection and Disposal Wells

Planning to convert or drill wells for water injection or effluent disposal? You might want to consider an injectivity #welltest before designing surface equipment. I usually recommend a 24 h constant rate test followed by a 96 h pressure fall-off test. For pressure transient analysis (#PTA) a steady rate (i.e. time) is more important than maximum volume. Subsurface pressure recorders have multiple benefits: they satisfy #AER Initial Pressure requirements, the test isn’t over if the well goes on vacuum, and we don’t have to calculate...

read more

D51: Water Injection and Disposal Wells

Planning to convert or drill wells for water injection or effluent disposal? #AER Directive 51 (D51), Section 8.1, outlines initial #welltest requirements for either: 1) Step-Rate Injectivity test, 2) an In-Situ Stress test, or 3) a Mini Frac’ test (DFIT). In my experience the Diagnostic Fracture Injection Test (#DFIT) out-performs the step-rate test for initiating breakover. Perhaps, with each step-rate, the formation actually starts taking water, dissipating frac’ energy? Whereas the rapid increase in pressure, delivered by a...

read more

Welltest 105: Thermal Data Diagnostics

Finally, Welltest Specialists believes #welltest analysis (#PTA) software should be upgraded to utilize the available temperature data for calculation of pseudo-pressure and pseudo-time variables. This should not pose a significant problem to programming code. Since thermal data are already there (essentially free for the taking), they might as well be used to better our interpretative insight and quantitative results: PTTA – Pressure-Temperature Transient Analysis… Contents of this blog were derived from the technical paper CIM...

read more

Welltest 105: Thermal Data Diagnostics

Welltest 105: Thermal Data Diagnostics

N2 p/T inversion curves Wet #gas (#LNG) temperature sensors (as in production logging) could easily be added to modern electronic pressure recorder designs. As the use of temperature data increases for welltest diagnostics, limitations of using recorder housing temperatures will quickly become apparent. As recorder carrier (housing) designs differ between manufacturers, so does heat capacity and thermal conductivity and, hence, apparent thermal behaviour, such as JT effects. The phenomena is illustrated by these N2 p/T inversion curves....

read more

Welltest 105: Thermal Data Diagnostics

Welltest 105: Thermal Data Diagnostics

Thermal Storage – Pressure Derivative Thermal Data Helpful for Identifying Valid Radial Flow Conditions. Temperature data recorded during a #welltest can be reflective of wellbore storage or afterflow effects and can help identify valid radial flow conditions. This #gas (#LNG) well #PTA example is the pressure derivative response for the thermal storage example presented last week. Note what appears to be very early radial flow followed by a transmissivity (kh/µ) change only one hour after shut-in. Thermal diagnostics suggests that...

read more