Well Cementing Diagnosis from Top Cement Pulsation Record

Document Type

Conference Proceeding

Publication Date

1-1-2001

Abstract

The paper reports on a feasibility study on post-cementing quality control using recorded data from Top Cement Pulsation (TCP). TCP is a novel technique for preventing gas flow after cementing. In this method small hydraulic pressure pulses (usually 100 psi.) are applied repeatedly at the surface into the casing annulus starting immediately after cement placement until the end of the cement transition time. The volumes of water pumped into the annulus and returned during TCP is monitored and converted to Top Cement Displacement Record (TCDR). These short duration pulses make the slurry columns shear and fluidize. The fluidization prevents under balance- a primary cause of gas migration after cementing. It had been postulated that TCDR might provide valuable information on the quality of cement setting in the annulus of the well. Consequently the record should some how be analyzed to determine fluid loss volume, initial/final position of top of cement and identify problems such as high fluid loss, bridging; identify presence of high temperature zones. The paper presents a diagnostic method based on recognition of TCDR patterns. From mathematical modeling of pulse transmission, different characteristic patterns have been derived. In the method the TCDR recorded from actual TCP data is compared with the expected TCDR. Then, a difference in the TCDR pattern between the expected and the actual TCDR is analyzed. From the analysis it can be determined what might have happened to the fluids placed in the annulus. Also included in the paper is validation of the diagnostic technique using field data collected from wells subjected to TCP. The wells were having relatively long interval of open hole with cement top far below the previous casing shoe. From the analysis it was possible to verify the progressive shearing of fluid columns during each pulse, the rate of fluid loss, the zone of fluid loss, end of cement thickening period, and top of cement.

Publication Source (Journal or Book title)

Proceedings - SPE Annual Technical Conference and Exhibition

First Page

613

Last Page

620

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