Abstract: Horizontal well has high productivity and good economic benefit. With the continuous development of offshore oilfields,the number of horizontal wells has increased. However,the horizontal wells have problems such as long horizontal sections,inability to be tested through conventional methods,high special testing cost,and low efficiency. Based on the current level of water injection wells in general,a set of layered water injection tools are submitted,and two radial and axis water injection channels are used to achieve water injection in heel or toe section. The inner diameter of the layered water injection string can meet the needs of later testing and measures. Taking well C in BZ Oilfield as an example,a layered water injection string is run into. The results of water absorption test and profile control test indicate that this string can achieve layered water injection in horizontal water injection wells,inhibit the sudden increase of water content in beneficiary wells,delay the natural decline of the oilfield,and thus improve the water flooding effect of the oilfield. It provides an important technical means for the efficient development of horizontal wells in offshore oilfields.

Key words: horizontal water injection well, water injection in sections, improving water injection profile, development effect