Design and Long-Term Production Performance of Frac Pack Completions in a Gulf of Mexico Deepwater Turbidite Field Having Inverted Sand-Shale Stress Contrasts: Case History

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSeveral sand control completions in the initial development of a Gulf of Mexico deepwater turbidite field failed prematurely when placed on production. After an extensive multi-discipline review of completion designs and procedures, the cause of these completion failures was determined to be an inverted sand-shale stress contrast, that is, shales were at lower minimum horizontal stress than adjoining sand layers. Direct evidence of this sand/shale stress reversal was obtained from mechanical strength property data derived from dipole sonic logs in two wells in this field.Frac pack completion design was modified to account for this sand/shale stress reversal by incorporating perforation standoff from adjacent shales and by using smaller pad volumes. The modified design was successful in achieving excellent frac packs in seven subsequent completions in this field. Long-term performance of these modified frac pack completions has been excellent.

Fracture Dissolution of Carbonate Rock: An Innovative Process for Gas Storage

“…Due to the higher stress in the limestone, the fracturing grates to areas of least stress, resulting in the taller fractures and lobes in the adjacent layers where the proppant flowed (Figures 73 and 74). Shale normally has a higher in-situ stress; however, inversions of this relationship have been reported (Shumbera et al, 2003 Figure 74 Fracture conductivity for a simulation where the limestone stress is 900 psi greater than the shale layers, 3:1 horizontal exaggeration.…”