As illustrated in FIG. When the predetermined maximum pressure was attained, the injection was stopped and the pressure was allowed to stabilize. Typically, care is exercised during drilling to prevent downhole pressure exerted by the drilling mud from exceeding a fracture initiation pressure of the formation. The parameters,in FIG. For example, the closure stress may be measured in the presence of a deployed downhole packer, and the net treating pressure may be measured to indicate how the fracture is propagating, namely crossing or non-crossing. The rate of leak-off is determined by the formation permeability. Founding Sponsor. An example of interpretation of a LOT to determine closure stress follows hereafter. The LOT procedure may be automatically or manually stopped before an uncontrolled hydraulic fracture is propagated into the tested formation as discussed in the following examples.
Formation Integrity Test is the method to test strength of formation and shoe by increasing Bottom Hole Pressure (BHP) to designed pressure. Leak Off Test (LOT).?
Leak Off Test – you pressure test shoe and formation until formation break down. Let's I explain. A Formation Integrity Test (FIT) is a test of the strength and integrity of a new formation and it is the first step after drilling a casing shoe track.
USA en. Postler, D.
pressure integrity test Schlumberger Oilfield Glossary
For the data shown in FIG. The measured pressures verses time for an extended LOT response may be analyzed using techniques previously set forth herein to determine these closure stresses. The LOT procedure may be automatically or manually stopped before an uncontrolled hydraulic fracture is propagated into the tested formation as discussed in the following examples.
The pressure is raised until the last casing shoe or formation is fractured as indicated by leak-off. Share this: Twitter Facebook.
USB2 Methods for determining formation strength of a wellbore Google Patents
Also known as leakoff test, a test to determine the strength or fracture pressure of the open formation, usually conducted immediately after drilling below a new.
Video: Formation integrity test drilling machines 5. IWCF : leak off test
The parameters,in FIG. Moreover, unexpected influx while drilling may be controlled by inflating downhole packer and circulating sufficiently heavy mud through diverter valves to balance measured pressure below the packer. If not, the core measured C 12 and C 13 values may be used to determine the constant x by rock class to apply to the log derived C 12 values to determine a continuous C 13 value.
Formation Integrity Test Definitions and Objectives Drilling Course
Hydraulic fracture reopening pressure and the estimation of maximum horizontal stress.
INTERAXON MUSE WIKI TABS
|The method of claim 1further comprising: detecting zero slope of the pressure derivative for a predetermined time period and then detecting that a change in pressure deviates from the unity slope by a predetermined value wherein the predetermined criteria includes detection of the zero slope of the pressure derivative for the predetermined time period and further wherein the test is terminated after detection of the change in pressure deviating from the unity slope by the predetermined value and determination that the predetermined criteria regarding the slope of the pressure derivative are fulfilled.
Postler, D. The LOT procedure may be automatically or manually stopped before an uncontrolled hydraulic fracture is propagated into the tested formation as discussed in the following examples. Step is optional; if a downhole packer is not used in the LOT, the entire wellbore below the casing shoe is tested to determine if any newly drilled formation is weaker than the segment drilled immediately below the casing shoe.
Then, the pressure derivative slope passes through zero slope during the growth of the fracture through the stress cage as the pressure derivative slope transitions to negative values.
In stepsubsequent action may be performed. If packers are not present in the BHA 96 or the drill string 72 as drilling progresses below the last casing shoeisolation of a specific interval to pressurize may be prevented.