Key Drilling Technologies for Metamorphic Buried Hill Reservoirs in Bohai Oilfield

A deep metamorphic buried hill in Bohai Oilfield has a great potential for hydrocarbon discoveries. However, complicated geological tectonic conditions and deeply buried target zone create a series of drilling challenges such as low rate of penetration (ROP), difficult reservoir protection, and high risk of wellbore instability and leakage. To solve the problems, a study was created to evaluate the optimization of drill bits and ROP improvement tools, wellbore stability technologies, reservoir protection technologies, positive displacement motor(PDM) optimization, and leakage prevention and plugging technologies. As a result, key drilling technologies for metamorphic buried hill reservoirs in Bohai Oilfield were developed, which were then successfully applied in seven exploration wells in this buried hill structure. As a result, the technical difficulties of the structure were overcome, i.e., the ROP was increased, and three exploration wells obtained high oil flow. The research and field applications indicate that the key drilling technologies can provide technical support for the exploration and development of deep metamorphic buried hill reservoirs in Bohai Oilfield.