Study On Ground Drilling Operational Anti-collision Observation For Offshore Cluster Wells’ Group

With fast development of the domestic offshore oil and gas, many fields that under the old arrangement of infill wells is facing the increasing risk of wellbore collision. For the early warning of anti-collision detection such as scan wellbore trajectory, MWD and artificial monitor was emerging calculation errors and hardly to meet the need for comprehensive development of oil fields. According to vibration theory of wave propagation, this paper put forward a new theory and method of Anti-collision monitor, through the top of the underground sensors which installed in the wellbore or casing to detect vibration signals and obtain the necessary underground dynamic information. Using these methods can monitor the drilling bit if close to the risk casing of adjacent wells or not and the possibility of collaboration to reduce the risk of collision between dill bit and casing.According to the working environment of some adjustment wells, the error ellipses of borehole intersect each other, this paper starts from the wellhole trajectory’s distribution, which has chosen to focus on the surrounding adjacent wells drilling though Compass. Several methods about vibration signature analysis and processing of collision is described as well as Anti-collision monitoring system. Focusing on different rock samples, different shaft structures, different communication media, the signal time and features between the different wells casing through lab experiments, so find the influencing factors to set up the relational model between the wave strength Q and the wells distance D when monitoring the casing.Based on the lab experiment theory, methods and equipment, we conducted a Anti-collision monitoring system scene test in the platform of SZ36-1 Craft in Bohai sea. By the key signal collection and analysis while shallow wells L11 closer to L5, it shows that the feasibility of using acceleration sensors and related equipment and software, also can obtained the relationship between underground signal characteristics and wells distance.This paper presents a vibration monitoring methods, which is a new effective technological means of anti-collision in wellbore that haven’t see similar technology at home and abroad. From the experimental study and application of the situation, it is able to achieve the relevant early warning function.