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Research on the phenomenon of collapse in casing and tubingDavid Hernández Morales Oil Technical Services6 October 2006ContentsIntroduction General Concepts Types of Collapse Leading Factors (case studies) Laboratory Tests ConclusionsResearch on the phenomenon of collapse in casing and tubingTenarisTamsa6 October 2006 David Hernández M.2IntroductionThe collapse of casing and tubing may lead tothe loss of a well. Studies on this issue have been of great interest to the oil industry.At present we have the technology and systems that can identify the most relevant contributing factors to this phenomenon which permits development of preventive measures that will save significant economic resources.Research on the phenomenon of collapse in casing and tubingTenarisTamsa6 October 2006 DavidHernández M.3General ConceptsCollapse can be defined as:The mechanical force capable of deforming a pipe as a result of external pressure.Research on the phenomenon of collapse in casing and tubingTenarisTamsa6 October 2006 David Hernández M.4General Conceptsro r ri Pi Peσr σtCollapseisacomplexphenomenon with a great many factors and parameters thatinfluence its effect.The classic theory ofelasticity allows us to determine the main radial and tangential stresses that act upon the pipe.Research on the phenomenon of collapse in casing and tubing TenarisTamsa 6 October 2006 David Hernández M. 5General Concepts15 14 13Collapse pressure (1,000 psi)12 11 10 9 8 7 6 5 4 3 2Average plastic collapseAPI5C3offersfourformulas which are able to predict the minimum collapse resistance value for thetype of failure: elastic, transition, plastic and yieldMinimum plastic collapseInitial plastic-elastic collapse modes Average elastic collapseMinimum plasticelastic collapseMinimum elastic collapseTransition collapse1 0 10 12 14 16 18 20 22 24 26 28 30Diameter/thickness ratioResearch on the phenomenon of collapse in casing and tubing TenarisTamsa 6 October 2006 David Hernández M. 6GeneralConceptsElastic Collapse Transition CollapsePlastic CollapseYield CollapseResearch on the phenomenon of collapse in casing and tubingTenarisTamsa6 October 2006 David Hernández M.7Leading FactorsThe collapse phenomenon is commonly attributed to suspected quality problems in the pipe. However, studies show there are a set of causative factors, such as: Wear on casing Wear due to buckling Increased externalpressure due to temperature Improper depressurization Geostatic loads (Overburden) due to plastic formations and tectonic activityResearch on the phenomenon of collapse in casing and tubing TenarisTamsa 6 October 2006 David Hernández M. 8Leading FactorsWear on casingThis factor is associated with the spinning of joints that are run in the drill string and the number ofdownhole trips that aremade. The level of wear on the casing is in relation to: Taking a long time when drilling High dog leg severity Stuck-pipe problemResearch on the phenomenon of collapse in casing and tubing TenarisTamsa 6 October 2006 David Hernández M. 9Leading FactorsTensile ForcesWear on casingThe reduction of the pipe wall thickness results in a reduction of the pipe’sLateral Force16” 2481 m 20” 1000 mmechanicalproperties. Severe wear on the casing has caused downtime, failed operations and loss of wells. Example of Zaap 7D wellHigh dogleg severityTorsional ForceStuck pipe 2625 m 2871 mCompression ForceResearch on the phenomenon of collapse in casing and tubingTenarisTamsa6 October 2006 David Hernández M.10Leading FactorsWear on casingD E P T1991 m batchesH Anomalies of (m) 2065 and 2144 m2144 m 2207 m2384 m16” - 2481 mcementPressure profile of casing collapse - 16”11 3/4” - 2868 m Casing wearResearch on the phenomenon of collapse in casing and tubing TenarisTamsa 6 October 2006 David Hernández M. 11Mechanical resistance to collapseMud 1.25 gr/ccLeading FactorsWear on casing11 3/4” Casing Tension Anomaly a 921 m Compression D E P T H (m)B.L 9 5/8”Research on the phenomenon of collapse in...