This paper presents the experiments and results of DCU in CLEF-IP 2009. Our work applied standard information retrieval (IR) techniques to patent search. Different experiments tested various methods for the patent retrieval, including query formulation, structured index, weighted fields, document filtering, and blind relevance feedback. Some methods did not show expected good retrieval effectiveness such as blind relevance feedback, other experiments showed acceptable performance. Query formulation was the key to achieving better retrieval effectiveness, and this was performed through assigning higher weights to certain document fields. Further experiments showed that for longer queries, better results are achieved but at the expense of additional computations. For the best runs, the retrieval effectiveness is still lower than for IR applications for other domains, illustrating the difficulty of patent search. The official results have shown that among fifteen participants we achieved the seventh and the fourth ranks from the mean average precision (MAP) and recall point of view, respectively.