Mechanistic Modelling of Sand Consolidation Treatment in a Sudanese Heavy Oilfield Using an Innovative Guar Gum Gel Recipe

Application of resin or cross-linked polymer that forms gel is one of the practiced sand control methods for the near wellbore sand consolidation. A proper design is essential in determining its successful application in the field. In this work a computational model is constructed the performance prediction of Gaur gum for application in a Sudanese oilfield.
Number of gel strength and sandpack experiments were carried out to evaluate the stability of guar gum to consolidate unconsolidated sandstone formations to simulate the treatment and post treatment conditions. Two correlations describing the properties and the outcomes of gel treatment were generated based these tests: To calculate the gel strength of a cross-linked guar gum and determine the post treatment altered permeability defines the well productivity.
A computational model was constructed from the developed analytical equations and
experimental data, which was then applied in the design of a sand consolidation treatment for an oil well in a Sudanese field. The gel strength profile around the wellbore was predicted by accounting the effect of dilution on both the guar gum and cross-linker concentrations. An additional pressure drop due to the partial plugging of near wellbore reservoir pores was calculated and presented. It was found that an additional pressure drop was more than 100 psi for 0.8 wt.% guar gum and 0.5 wt.% cross-linker. These optimal concentrations were selected using a plot to optimize the tradeoff between having a strong gel and minimizing positive skin factor. An acceptable gel strength of 7 on the gel scale is formed at these concentrations along
with a 30% drop in well post treatment productivity. It was also shown that the resulting productivity of the well is sensitive to both guar gum concentration and invasion radius, which becomes more sensitive to both factors as the guar concentration increases.