Issued Patents All Time
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5957197 | Downhole cut-off valve used for cementing | Xianchang Xia, Fuyan Zhang, Xijun Tian, Hong Li | 1999-09-28 |
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5957197 | Downhole cut-off valve used for cementing | Xianchang Xia, Fuyan Zhang, Xijun Tian, Hong Li | 1999-09-28 |