Cross-linked hydraulic fracturing fluid gel can induce high damage in the fracture when left for a long time. Any residual gel not produced back reduces the conductivity of the fracture and the well productivity, leading to an extended flowback for a cleanup operation, which is not cost-effective. The objective of this study is to assess the cleanup operation effectiveness by conducting a laboratory testing on the flowback fluid samples from hydraulically fractured three development wells to optimize flowback duration and cost, and minimizing formation damage; and thereby enhancing well productivity. These wells are drilled in a clastic Devonian gas reservoir in Saudi Arabia. This reservoir has a range of permeability varying from tight (0.1 mD) that requires stimulation to highly prolific (greater than one Darcy) that produces naturally. The laboratory analysis technique that was used for assessing the cleanup effectiveness is based on determination of the polymer content in the flowback of the fracturing fluid with a size exclusion chromatography (SEC). The technique provides the polymer concentration in the return fluid in a series of samples collected throughout the cleanup operation. The polymer strength of the residual fracturing fluids can then be inferred from the polymer concnetration and the production performance. This study shows that the SEC technique is effective to qualitatively determine the residual polymer content. The results are useful in establishing trends for the effective flowback practices based on different reservoir and fracture characteristics. Using the laboratory results to optimize these parameters, formation damage can be minimized and well productivity will be ultimately enhanced.
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