Tubing pressure higher than casing one

[kochichiro]

Hello guys, I have following question. We have gas well flowing with 1.43 MMscf/day rate. During flow period tubing pressure is 622.84 psia and casing pressure is 616.01 psia. At the end of 96 hr build-up, tubing pressure is 1257.77 psia and casing one is 1218.23 psia.

So why do we have such difference between the tubing and casing pressures? I mean it is normal to gas well producing water to have casing pressure higher than tubing one, but in our case we have opposite situation.

We do not have packer between casing and tubing. Static pressure surveys with resistivity device show 90 % of water content at the bottom of tubing during flow period and 0 % at the end of build up.

Generally, it appears that we have lighter fluid in casing than in tubing. Does it mean that we have casing leak?

[ELgharib]

Should be U-tube effect...Slowly and slightly bleed off the casing pressure(say 150 Psi) and see if the pressure builds up to the same value.

[kochichiro]

Thanks for your reply, we'll try to do this.

[Land_Mark]

The differences in pressure are minimal to negligible. In a well with this configuration, there is no way to identifying the annulus fluid, unless you have gauges measuring the pressure at the bottom of the tubing in both the annulus and bottomhole. This minor difference could be a result of differences in calibration of both gauges; i suggest you use identical gauges that have undergone the same calibration procedure. It also also poor integrity practice to leave the casing exposed to well fluids, which shorten the life of your well.

Hello guys, I have following question. We have gas well flowing with 1.43 MMscf/day rate. During flow period tubing pressure is 622.84 psia and casing pressure is 616.01 psia. At the end of 96 hr build-up, tubing pressure is 1257.77 psia and casing one is 1218.23 psia.

So why do we have such difference between the tubing and casing pressures? I mean it is normal to gas well producing water to have casing pressure higher than tubing one, but in our case we have opposite situation.

We do not have packer between casing and tubing. Static pressure surveys with resistivity device show 90 % of water content at the bottom of tubing during flow period and 0 % at the end of build up.

Generally, it appears that we have lighter fluid in casing than in tubing. Does it mean that we have casing leak?

[Land_Mark]

The differences in pressure are minimal to negligible. In a well with this configuration, there is no way to identifying the annulus fluid, unless you have gauges measuring the pressure at the bottom of the tubing in both the annulus and bottomhole. This minor difference could be a result of differences in calibration of both gauges; i suggest you use identical gauges that have undergone the same calibration procedure. It also also poor integrity practice to leave the casing exposed to well fluids, which shorten the life of your well.

Hello guys, I have following question. We have gas well flowing with 1.43 MMscf/day rate. During flow period tubing pressure is 622.84 psia and casing pressure is 616.01 psia. At the end of 96 hr build-up, tubing pressure is 1257.77 psia and casing one is 1218.23 psia.

So why do we have such difference between the tubing and casing pressures? I mean it is normal to gas well producing water to have casing pressure higher than tubing one, but in our case we have opposite situation.

We do not have packer between casing and tubing. Static pressure surveys with resistivity device show 90 % of water content at the bottom of tubing during flow period and 0 % at the end of build up.

Generally, it appears that we have lighter fluid in casing than in tubing. Does it mean that we have casing leak?