渤中19-6凝析气田太古界潜山储层地质模式及开发策略

Geological model and development strategy of Archean buried hill reservoir in BZ19-6 condensate field

综合运用岩心、测井、地震、野外露头及生产测试资料对渤中19-6太古界潜山储层地质模式进行了分析。研究发现,渤中19-6太古界潜山储层纵向分为风化带和内幕带。风化带受构造和风化淋滤作用双重控制,发育构造缝、风化缝、溶蚀孔隙等储集空间类型,裂缝整体发育呈网状,储层连通性好,呈“似层状”分布模式。内幕带主要受高角度断层控制,储集空间以构造缝为主,内幕带储层沿高角度断层呈“带状”分布模式。针对渤中19-6潜山高含凝析油、低地露压差以及低孔低渗的油气藏特征,提出采用周期注气的开发方式提高凝析油采收率;基于潜山地质模式,采取储层顶部注气、中下部采气的立体注采井网。为减缓气窜,增加注气波及面积,提高单井产量,结合数值模拟结果,井网部署采取井轨迹与裂缝斜交45°角、注采井主流线方向与裂缝走向呈一定夹角的布井原则。

Based on the data of core,logging,seismic,field outcrop and production test,the geological model of Archean buried hill reservoirs in BZ19-6 area is analyzed.It is found that BZ19-6 Archean buried hill reservoir is divided into weathering zone and inner zone longitudinally.The weathering zone is controlled by both tectonism and weathering&leaching,and the reservoir space is dominated by structural fractures,weathered fractures and dissolution pores,with fractures developed in network as a whole.Its reservoir connectivity is good,showing a“stratoid”distribution pattern.The inner zone is mainly controlled by high angle faults,and the reservoir space is dominated by structural fractures.The reservoirs in the inner zone are distributed in a“zonal”pattern along high angle faults.In view of the characteristics of BZ19-6 buried hill reservoirs with high condensate content,small difference between dew point pressure and formation pressure,low porosity and low permeability,the method of periodic gas injection is proposed to improve condensate recovery.At the same time,based on the buried hill geological model,the three-dimensional injection-production pattern of gas injection at the top and gas recovery at the middle and lower parts of the reservoir is adopted.In order to slow down gas channeling speed,increase gas injection swept area and improve single well production,the following well pattern arrangement plan is adopted in combination with the numerical simulation results the well trajectory is oblique to the fracture at an angle of 45°,and the main stream line direction of injection-production wells is at an included angle with fracture strike.