Directional Drilling Reaming Technology in the Shallow Formation of Well A14H in the LD22-1 Gas Field

In order to solve problems that occurred when drilling shallow soft formation in the LD22-1Gas Field, in the Yinggehai Basin of the South China Sea,including problems in directional drilling,reaming,building angle, borehole collision of the adjacent wells,a new technology was developed.It involved drilling a small-sized pilot hole at first,and then using special three-stage reamer to directionally reaming it,followed by then running surface casing.Combined MWD with gyro inclinometer,a small pilot hole of φ250.8 mm was drilled with directional drilling tools in Well A14H in LD22-1 Gas Field,and then it was reamed to the φ444.5 mm by the special reamer with three-stage reaming sizes of φ254.1 mm×φ349.3 mm×φ444.5 mm,finally the φ339.7 mm casing was run in hole and cemented.Drilling practices showed that the technology successfully prevented the borehole from colliding in cluster wells in shallow formations successfully.It also ensured the effect of directional drilling and building up,and eliminated the unfavorable effect of reamer on building up in pilot hole.The study concluded that it would be an useful reference for drilling in similar shallow soft formations.