The Influence Of The Reservoir Heterogeneity For Development Efficiency On Extra-heavy Oil Reservoir In The Second And Third Member Of Shahejie Formation In Block Cao4

The second and the third member of Shahejie formation in block Cao4 belongs to the special viscous crude oil reservoir with serious heterogeneity. The main sedimentary sand body is delta front sheet sand, with serious heterogeneity of the reservoir.This reservoir is still in the early stage of development, during which the water flooding problems affects the development effect seriously, and restrains the efficient and smooth development of the field oil. This article is based on the fully understand of the reservoir's basic character of the area and analysis of the reservoir's heterogeneity, focus on the effect on the development of reservoir's heterogeneity, figure out the water flooding problem which restrain the development, and on the basis put forward on the adjusting direction and suggestion.This article analyses the reservoir's geological character of the area. Making a brief assay of the strata developmental, structural, sedimentary and the reservoir character of the 6 sublayers which belong to the objective interval. Based on the analysis of the reservoir's geological character. The article makes a detailed study of the reservoir heterogeneity, barrier bed and intercalated bed heterogeneity, crude oil heterogeneity. Through the study, the reservoir heterogeneity in this study field is relatively weak, this may have some effect on the development. Barrier bed presents strong heterogeneity especially for barrier bed between the layer system, thin and showed partial loss of potato-sharp. The high destructive effect of the thermal development induces the barrier bed fail to isolate the up and down layers. The resort water which caused by steam stimulation from the upper layer system breaks through the down layer system and causes some of the exploitation wells high water cut. When well startup, it seriously affects the development effect. The heterogeneity of the physical property of crude oil also has an important influence on the heavy viscous crude oil reservoir development. The property of the crude oil determines the producing method, three production methods are adopted in the study field:cold production well(borehole heating measure and strata unheating), thermal production well{strata heating(steam stimulation injection) ,borehole auxiliary viscosity reducing}, cold production transfers to thermal(the productivity decrease after using the cold production method for a period of time, then transferring to thermal ). Areal heterogeneity of the crude oil's property affects the development effect directly. Through the analysis of the reservoir sensitivity potential factor and experiment, we worked out Clay minerals and carbonate minerals has a high level. Sensitivity represents a weak speed-sensitivity, weak to moderate water-sensitivity, moderate on the weak side salt-sensitivity, weak acid sensitivity and weak alkali-sensitivity. Based on the analysis of the reservoir heterogeneity impact on the development, we figured out the existing problems and bought forward adjustment direction, set horizontal well at the partial imperfect well net, designed the horizontal wells can both increase the single well controlled reserves and avoid water intrusion problem caused by the barrier bed adjustment. By the analysis of the five new designed horizontal wells, we optimize two wells to carry out geological design in the three dimensional modeling, which adopt the reservoir engineering scheme for target pre-determination.It showed that daily oil production 118.2t, daily fluid production 503.0t, cumulative oil production 39.6×104t, composite water cut reached at 76.5%, oil production rate reached 0.53% after 5 years, degree of reserve recovery reached 5.9%.