Well testing
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Well testing
I am working in a offshore exploration drilling project. We will drill oil and gas vertical wells to 1600-1800 mMD using a Jack Up. The operating daily cost is stimate in 350.000 USD/day.
Wells will be test using DST en 7" cased hole. Probably it will neccesary perform 3 or 4 DST (because we have 3 o 4 diferente productions zones).
And here start my problems. 1.- is it better use 3-1/2" or 2-7/8" tubing??.
2.- And the most important: Wich thecnology to use. SRO?, memory gauge?, TCP, etc, etc.
Thanks in advance for your opinions and information where I can get specific details about down hole tools and their aplications. Regards.
Wells will be test using DST en 7" cased hole. Probably it will neccesary perform 3 or 4 DST (because we have 3 o 4 diferente productions zones).
And here start my problems. 1.- is it better use 3-1/2" or 2-7/8" tubing??.
2.- And the most important: Wich thecnology to use. SRO?, memory gauge?, TCP, etc, etc.
Thanks in advance for your opinions and information where I can get specific details about down hole tools and their aplications. Regards.
Hi,
You have pressure, depth and other data , you can predict the flow rate assuming the hydrocarbon is oil or gas using nodal analysis. from that analysis, you can see which tubing size is required ( rough approximation).
2. SRO (surface Read Out)...actually this is the memory gauge but it's connected by wireline to surface so we can monitor the reservoir pressure.
it's off course better than if you use memory gauge only. You can stop build up test by monitoring the reservoir pressure (not increasing anymore) so you can save the rig time. The problem is you need to pay more to service company for renting the SRO.
You have 3 or 4 DST...so you have to use wireline perforation gun because if you use TCP, you need very long rat hole at the bottom of the well to put the gun after fired.
You have pressure, depth and other data , you can predict the flow rate assuming the hydrocarbon is oil or gas using nodal analysis. from that analysis, you can see which tubing size is required ( rough approximation).
2. SRO (surface Read Out)...actually this is the memory gauge but it's connected by wireline to surface so we can monitor the reservoir pressure.
it's off course better than if you use memory gauge only. You can stop build up test by monitoring the reservoir pressure (not increasing anymore) so you can save the rig time. The problem is you need to pay more to service company for renting the SRO.
You have 3 or 4 DST...so you have to use wireline perforation gun because if you use TCP, you need very long rat hole at the bottom of the well to put the gun after fired.
Thanks a lot for your early reply.
I have a couple of things more: I have been estudied a well drilled years
ago close to our future operations. They drilled to 1722 m, 7" casing. (float collar in 1708 m) a) 4 gun/ft 1671-1676, test, bridge plug. b) gun 1658-1659/1661-1665.5, test, brid plug in 1656. and c) gun 1648-1650/1651-1653 and test., then abandonment. We will do similar program.
1.-Looking this information what do you think about to use tcp??
2.- SRO means that it will neccesary land the tubing and install x-mas tree??
3.- If there no surface flow (ej. the fluid inside the tubing dont reach surface. should you recommend to use SRO?
4.- Suppose the studies says that with 2.7/8" tubing is enough (so I can running 5-1/2" casing). however, some service company says is better to test inside 7" (better information, more easy to get the tools, etc.) what do you think??
I know, are many questions. sorry.
I have a couple of things more: I have been estudied a well drilled years
ago close to our future operations. They drilled to 1722 m, 7" casing. (float collar in 1708 m) a) 4 gun/ft 1671-1676, test, bridge plug. b) gun 1658-1659/1661-1665.5, test, brid plug in 1656. and c) gun 1648-1650/1651-1653 and test., then abandonment. We will do similar program.
1.-Looking this information what do you think about to use tcp??
2.- SRO means that it will neccesary land the tubing and install x-mas tree??
3.- If there no surface flow (ej. the fluid inside the tubing dont reach surface. should you recommend to use SRO?
4.- Suppose the studies says that with 2.7/8" tubing is enough (so I can running 5-1/2" casing). however, some service company says is better to test inside 7" (better information, more easy to get the tools, etc.) what do you think??
I know, are many questions. sorry.
Breifly :
1- There is no need for SRO, because it need more time for rig up and rig down. you can predict the flowing period and shut in period from the flow performance, is it flowing naturally or not. if flowing is it stable or not, is it sensitive for chock size changing or not ??
you can monitor the well head pressure while flowing or shut in period which reflect the downhole pressure. and you can stop the shut in period if you reached the stabilized WHP
2- in exploratory wells it is better to use 3 1/2" tubing size for testing to get the maximum potential from the well. and also give you a chance to RIH with coil tubing if the well does not flowing naturally.
3- if you are going to perforate a clean sandstone so you need maximum penetration like 4 5/8" HMX of Schlumberger and no need for high Shot Per Foot (SPF). if you are going to perforate a fractured limestone you dont need a deep penetration .... etc. depends on your case
4- i prefere to make underbalance 1500 Psi in case of Sandstone
5- There is no need for rate hole, so you can use shot and pull in perforation
Sorry for long answer BUT forgive me because it is my JOB
1- There is no need for SRO, because it need more time for rig up and rig down. you can predict the flowing period and shut in period from the flow performance, is it flowing naturally or not. if flowing is it stable or not, is it sensitive for chock size changing or not ??
you can monitor the well head pressure while flowing or shut in period which reflect the downhole pressure. and you can stop the shut in period if you reached the stabilized WHP
2- in exploratory wells it is better to use 3 1/2" tubing size for testing to get the maximum potential from the well. and also give you a chance to RIH with coil tubing if the well does not flowing naturally.
3- if you are going to perforate a clean sandstone so you need maximum penetration like 4 5/8" HMX of Schlumberger and no need for high Shot Per Foot (SPF). if you are going to perforate a fractured limestone you dont need a deep penetration .... etc. depends on your case
4- i prefere to make underbalance 1500 Psi in case of Sandstone
5- There is no need for rate hole, so you can use shot and pull in perforation
Sorry for long answer BUT forgive me because it is my JOB
Thanks very much for the usefull information. Now a have more clear the way.
In our case is Sandtone.
One more thing. Is possible think in to get some information comparing the different down hole tools offering currently by the market??. I say this because could be important before we will perform a "Call for tender".
Thanks a Lot.
In our case is Sandtone.
One more thing. Is possible think in to get some information comparing the different down hole tools offering currently by the market??. I say this because could be important before we will perform a "Call for tender".
Thanks a Lot.
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ahmed abdelaziz
- Posts: 1
- Joined: Sun Mar 16, 2008 5:46 am
These are some comments and I am waiting for your opinions:
1- It is difficult to change the DST design even with monitoring the WHP stabilization or change, also you may need to run the DST for along stabilization to detect the boundaries. I know that a reservoir engineer on the site can make the decision for decreasing or increasing the periods but I think the better is to predict the performance of the DST by knowing the estimated pressure, rock properties and distance from boundries and hence using one of "Well test analysis software" you can simulate the results to know the periods of flow and shut in
(If any one got PanSystem or Saphire or any other well test analysis software i will be grateful if he uploaded it because I really need it)
2- Underbalance in case of sandstone is good to decrease the damage for the zone but in case of exploratory wells, drilling engineers find it some what risky because they still can not have a good prediction for the formation pressures and characteristics.
1- It is difficult to change the DST design even with monitoring the WHP stabilization or change, also you may need to run the DST for along stabilization to detect the boundaries. I know that a reservoir engineer on the site can make the decision for decreasing or increasing the periods but I think the better is to predict the performance of the DST by knowing the estimated pressure, rock properties and distance from boundries and hence using one of "Well test analysis software" you can simulate the results to know the periods of flow and shut in
(If any one got PanSystem or Saphire or any other well test analysis software i will be grateful if he uploaded it because I really need it)
2- Underbalance in case of sandstone is good to decrease the damage for the zone but in case of exploratory wells, drilling engineers find it some what risky because they still can not have a good prediction for the formation pressures and characteristics.