Integrative Evaluation Of Hard-to-Recover Reserves In Liaohe Oil Province

At present, Liaohe oil province is facing a rigorous situation. Most of the major oil producing blocks developed by water flooding had entered "two-high" stage (high water cut and high recovery percent of reserves). Heavy oil thermal recovery reservoirs are now in later period of cyclic steam stimulation (higher cycles). Most of blocks in Shenyang oilfield are in a period of fast declining in production. In addition, under present development mode, the room for reconciliation in matured oilfields is limited, and the effectiveness of reconciliation and measures is becoming worse year by year, which will surly result in a big decrease in production of both old wells and new wells. This is an important reason of big decrease in production in Liaohe oil province. In order to keep continuous and stable development in Liaohe oilfield, reserve resources are of vital importance. By the end of December 2001, proved reserves which are hard to recover in Liaohe oil province was 0.489 billion tons, most of such oil blocks have features of low permeability, deep, difficult, heavy, and small. For the purpose of making reasonable use of this part of resources and tapping its potential, this study is conducted.This study involves seven parts. Part one is about literature overview, which introduces investigation of hard-to-recover reserves both at home and abroad. A large volume of data both at home and abroad has been searched, the characteristics, evaluation method and development feasibility of hard-to-recover reserves are understood more thoroughly. Part two is about features of hard-to-recover reserves in Liaohe oil province, which are: uncertain, low permeability, deep, difficult, heavy, small and offshore. This will increase difficulty to recover. Part three deals with Development feasibility evaluation for hard-to-recover reserves, development feasibility is demonstrated for this type of reserves in Liaohe oil province from aspects of geology, engineering and economy. In order to guarantee evaluation accuracy, an integrative evaluation system for hard-to-recover reserves has been developed. Part four studies evaluation of reserves classification. On this basis, classification evaluation of hard-to-recovers has been established wish consideration of all aspects, efficacy and discrete. Part live, the study of integrative evaluationmethod for hard-to-recover reserves. Which includes fuzzy analytical hierarchy process and gray clustering. At the same time, evaluation database for hard-to-recover reserves has been set up, computer software has been compiled and work efficiency has been improved. Part six studies is about application of method and achievement analysis. In this part, two classification evaluation methods are used to carry out case analysis for more workable hard-to-recover reserves. These methods had applied to productivity construction in 2000-2001. 19 blocks including Hainan3, Leng602, Shul area, xiao 23 and Du32, had been chosen to implement productivity construction, and a productivity of 1.698 million tons per year was realized. Productivity ratio and producing degree of reserves were both higher than 80 %. This shows that the method was practicable for evaluation of hard-to-recover reserves. Part five is a conclusion.This study proceeds from the rigorous situation of Liaohe oil province. Evaluation of development feasibility and classification are carried out for hard-to-recover reserves. Through combing technological and economical index, integrative study has been carried out for determining index collection of reserves classification evaluation, and for weighting of evaluation index and setting up of evaluation model. This study has reached certain level.Through integrative evaluation for hard-to-recover reserves, notable successes have been achieved: 1) by relying on science and technology advances, extra-heavy oil resources is produced gradually, which is of vital importance for mitigating the shortage of reserve resources for productivity of new blocks and heavy production duty of old...