The effects of thin objects (fractures/barriers) on pressure distributions and displacement performances in staggered and direct line-drive patterns with uniformly and stochastically distributed objects at different density and length distributions are studied. Tracer breakthrough and well productivity are used to characterize the configuration of thin objects in the patterns. In most cases examined, tracer breakthrough time is more sensitive to the presence of thin objects than the well productivity. It is also found that representing fracture systems as equivalent anisotropic media may lead to erroneous pressure-distribution predictions around a well. The study was carried out by using the complex variable boundary element method (CVBEM), which yields both the potential and stream functions simultaneously, and is suitable to track displacement fronts in the presence of thin objects. Singularities caused by such objects are expressed analytically through the conformal-mapping technique.