Key Drilling Technologies for Ultra-Shallow Horizontal Wells in the Jihua-1 Block of Jilantai Oilfield

During the drilling of ultra-shallow horizontal wells in the Jihua-1 Block of Jilantai Oilfield, some problems were encountered due to the soft Cretaceous strata in the upper part and the high hardness, poor drillability and strong heterogeneity of the gneiss strata in the lower part. In these wells, the build up rate can not be guaranteed, the drilling cycle is long, the horizontal sections are difficult to extend in hard strata, and the later completion casings are hard to run safely. In the light of this, the drilling technologies for ultra-shallow horizontal wells were studied. Considering the geological characteristics of this region, the rock mechanics parameters of gneiss were adopted in simulation and the casing program was optimized. A customized PDC bit was designed and the bottomhole assembly and speed-up tools were optimized. In addition, supporting technologies such as float casing running and environmentally friendly low-solid drilling fluid which would effectively protect the reservoir were integrated. Thus, key drilling technologies were formed for ultra-shallow horizontal wells in the Jihua-1 Block of Jilantai Oilfield. They were applied to four wells in the field with no downhole complexity occurred, suggesting good well completion results. These technologies can provide technical support for the future development of horizontal wells in this block.