Abstract:
Yangshuiwu buried hill is one major exploration area in Jizhong depression and its exploration prospect is promising.Well AT1x is a wildcat well in this area, and its total depth is 5 496 m.The reservoir temperature is over 180 ℃ and the formations drilled in this well are lithologically complex.And the wellbore operation is faced with a series of difficulties in terms of rate of penetration (ROP) improvement, borehole wall anti-sloughing, reservoir evaluation, reservoir stimulation, etc.In this paper, the key wellbore technologies for the exploration and development of high-temperature buried hill oil reservoirs were researched.The first is drilling fluid technology.Fractures are discovered through scanning electron microscope (SEM), and correspondingly the drilling fluid of KCl composite salt is added with polyamine inhibitor and nano anti-sloughing blocking agent.Thus, the blocking capacity of drilling fluid is improved and the average hole enlargement ratio is less than 10%.The second is drilling bit selection technology.The PDC bit and its support ROP improvement tool are selected, and consequently the average ROP is increased to 4.11 m/h while the average ROP of its comparable well is 1.94 m/h.The third is logging technology.A series of integrated conventional logging+imaging+dipole acoustic imaging logging technologies are adopted.As a result, the fractures and cavities near the well can be also described precisely so as to provide the basis for reservoir evaluation and fracturing layer selection.And the fourth is fracturing stimulation technology.The SRV acid fracturing technology suitable for high-temperature fractured carbonate reservoirs is developed by combining in-depth fracture communicating technology with stimulated reservoir volume (SRV).And by virtue of this technology, daily gas production and oil production of Well AT1x after acid fracturing is kept at 41×10
4 m
3 and 71 m
3, respectively during the production test.And as a result, new exploration breakthrough is realized in the deep buried hills in northern Jizhong depression.These technologies settle down the wellbore difficulties during the development of Yangshuiwu buried hill in Jizhong depression, and provide the candidate technologies for the development of high-temperature fractured oil reservoirs by means of deep wells.