Bionic Drilling Fluid Technology for Borehole Strengthening Used in Well Jia-3-21X

The Well Jia-3-21 X is located in the Jia-3 fault in the northwest of the Gaojiapu structure in Huabei Oilfield.The well penetrated several faults.The ShahejieFormation penetrated is consisted of long section of salt and gypsum interlayers.Borehole collapse, mud losses, tight hole and sticking of wireline logging tools and drill pipes have occurred during drilling operation.A bionic drilling fluid, capable of strengthening the borehole wall, was introduced to solve these problems.In laboratory studies, NaCl was introduced into the bionic drilling fluid to enhance its inhibitive capacity.Hot rolling test with salt rocks gave cutting recovery of 85%, and gypsum rocks gave cutting recovery of 95%.Contamination by 0.6% CaCl₂, had only slight influence on the properties of the fluid.Field application of this drilling fluid on the Well Jia-3-21 X was very successful, with average hole enlargement decreased by 62%, and time of drilling greatly shortened.