Dynamic Evaluation of Flow Unit Based on Reservoir Evolution: A Case Study of Neogene Guantao Ng3 Formation in M Area, Gudao, Bohai Bay Basin

Table 3

Division of development period of the study area.

Period	Start and end date	Number of wells/well	Water injection well/well	Period characteristics
Period 1	1973 ~ 1983.5	75	5	At the initial stage of production, the water injection time is short, and most of them are from oil production to water injection, with small water injection volume.
Period 2	1983.5 ~ 1991.4	121	23	The study area has entered the period of water injection development.
Period 3	1991.4 ~ 2000.2	139	30	The moisture content reaches 90%.
Period 4	2000.2 ~ 2017.7	145	36	Before well pattern exchange.
Period 5	2017.7 ~ today	145	24	The well pattern streamline changes by 40° as a whole.