Acoustic and Nuclear Wireline Logging Validation of Shape Memory PolymerScreen Expansion

摘要

A new shape memory polymer(SMP)sandface completion is entering the market as an alternative to gravelpacks.The SMP activation has been well established in the laboratory and successful field deployments hasbeen reported.To confirm the SMP material is fully expanded and to enable long term stability assessment,a practical in-situ evaluation method is needed.Three acoustic and two nuclear services are evaluated fortheir ability to detect SMP expansion in a simulated formation.A downhole equivalent in-situ test environment was built for purpose with a section of limestone blocksdrilled to 8.5 in.gauge hole and a joint of unexpanded SMP screen placed within.Two cased-hole CBLservices evaluated ultrasonic guided mode attenuation response in the base perforated pipe.These modesconsisting of two lamb modes,the compressional(S0)and the asymmetric(A0 flexural),along with theshear horizontal(SH)mode.Additionally,a multipole acoustic tool was utilized to analyze the responseof both the refracted modes,compressional and shear,and the guided modes,casing tube and flexuralwaves.Nuclear services employed pulsed neutron and compensated neutron techniques.The SMP was thenactivated and a second pass logged for each technique.The limestone was removed from the SMP to visuallyverify expansion.The logs before and after expansion are compared.In conclusion,several measurements provided good indication of the SMP expansion.The ultrasonicguided mode analysis demonstrated attenuation response increases,with the largest change observed forthe A0 mode when compared to the S0 compressional response.Of the lower frequency multipole acousticmethods,the guided casing tube wave demonstrated the greatest response,even greater than the ultrasonic,particularly in the low frequency range below 3 kHz.Generally,excitation modes with particle motionparallel with the base pipe were found to attenuate least while those with normal components displayedthe largest change.This is likely due to compression of the base pipe and metal screen layers because theSMP begins to exert force in all directions when it reaches gauge hole,which is short of full expansionas designed.The pulsed neutron(PN)logs provided a qualitative,yet clear verification of expansion when comparingmeasurements sensitive to hydrogen concentration.The SMP is an extremely low density organic moleculewith hydrogen concentration less than that of water.Comparing before and after PN logs indicates that a change in the hydrogen concentration occurred as a result of SMP expansion.Compensated neutron did notshow sensitivity to expansion of the polymer.This is the industry's first logging validation of shape memory polymer activation in the annulus ofa simulated downhole environment.Prior attempts with a variety of logging services and a simpler testenvironment were inconclusive.