Study Of Sazhong Oilfield Development Rule And Production Replacement Method

Since 2008,the areas of Sazhong Oilfield has gradually entered the secondary development,up to September 2015,the comprehensive water cut in the whole area reached 95.70%,which the comprehensive water of water flooding areas is 94.63%,and the comprehensive water of tertiary oil recovery is 96.77%,the oil field has entered the water flooding and polymer flooding and the conventional wells and small well distance coexistence of high water level development stage,the law of development have changed significantly,we need to reunderstand the law of development of water flooding in Sazhong Oilfield,and provide the basis for the forecast and production plans for the oilfield development.This paper studied the variation of the reservoir water cut of Sapu oil layer and Gaotaizi layer in Sazhong oilfiled,studies show that the water cut rising rate of Sapu oil layer is 0.21%~0.53% when its water cut reaches 94%,when the water cut of Gaotaizi oil layer is 94%,the water cut rising rate is 0.44%~0.99% in conventional well spacing aera and 0.68% ~0.88% in small well spacing aera.Based on the calculation method of natural decline rate,we considered the influence of new wells in two years,drilling and shut,using,plugging,polymer flooding effect,fluid production changes and casing damage,worked out the production of water flooding without other measures,analyzed the production decline rate variation of water flooding and calculated the average decline rate of Sazhong oilfield is 7.46%.According to the rule of decline rate and influencing factors of the various aera in Sazhong oilfield,we divided 12 blocks into 4 types.At present,the decline rate of three areas interfered by water flooding is7.04%~7.12%,while the normal aeras' is 6.42%~6.82%,the small spacing areas' is 9.10%~10.70%,and the casing damage areas' is 11.12%~13.14%.Based on the water flooding decline rate,the water flooding production of Sazhong oilfield during the "13th Five-Year Plan" was predicted.At the same time,the material balance method was used to predict the change of tertiary oil production of Sazhong oilfield.On this basis,with “12th Five-Year” annual average reserves of chemical flooding and annual maximum reserves of chemical flooding as the "13th Five-Year" new investment target reserves of chemical flooding,the conditions of before the chemical flooding water cut,fluid production rate,production decline rate of buffer areas and recovery degree of chemical flooding stage are taken as constraint conditions,the production of succession optimization mathematical model was established,which predicted the output of "13th Five-Year " in the next five years of Sazhong oilfield,we obtained that at the end of the "13th Five-Year" the annual oil production is respectively 661.55×104m3 and 768.34×104m3 with 175 m well spacing.