Integrated Subsurface and Fracturing Treatment Analysis for Proppant Placement Enhancement in Tight Clastic Horizontal Well Fracturing

Abstract

Fracturing treatments in horizontal wells is challenging and the challenges are compounded in reservoirs influenced by high tectonic effects. Situations are faced where either rock breakdown or sufficient fracture propagation is not achieved. Near-wellbore complexities also lead to insufficient injection rate, post-breakdown, to place proppant. In this work, an in-depth diagnosis of factors affecting fracturing success enabled proposing potential solutions. A total of 106 fracturing stages were analyzed across 14 wells with a structured database created with 52 fracturing-relevant parameters. These included different phases of the well such as drilling and completion, processed openhole logs, perforation details, fracturing treatment parameters, and pressure diagnostics data. A detailed diagnostic study was then conducted to dissect and diagnose the factors that were affecting the successful fracture placement. The integrated study investigated 11 areas of diagnosis: (1) geology and reservoir characterization, (2) geomechanical aspects, (3) drilling fluid challenges, (4) completion type, (5) topographical analysis of tectonic stress components, (6) rock breakdown pressure, (7) surface pressure limitation related to fluid friction, (8) induced poroelasticity, (9) viscosity-dominated propagation, (10) formation pressure capacity leading to horizontal or T-shaped fractures, and (11) perforation strategy and placement. Multiple correlations were obtained during the diagnostic phase and revealed significant underlying mechanisms. The next phase was the implementation of the solution spectrum with 14 solutions: (1) image logs to understand impact of natural fractures; (2) lamination quantification; (3) textural analysis based on sand counting; (4) drilling fluid and overbalance optimization; (5) breakdown acid; (6) perforation optimization; (7) abrasive perforating and circular notching; (8) mud damage dissolution system (;9) low rate, low friction, viscous pill; (10) linear gel hybrid treatment; (11) channel/pulsed fracturing; (12) high-density fluid; (13) fiber-laden slurry; and (14) fluid-loss additives. An engineered workflow was proposed to be used at the wellsite. The workflow captures all the solutions in context of injection achieved at each step. The solution spectrum allowed enhancing the placement success by 40 to 50%. This work addresses the biggest challenge in eastern hemisphere in their tight gas clastic reservoirs during exploration and development strategy. The comprehensive subsurface integration with advanced image logs, strategic geosteering, drilling fluid optimization, fracturing techniques, technologies, and chemistry is unique in the industry with significant realized value.