Research And Application Of Cementing Technology For The Section Of Zaonan Fault Block

With the development of oil and gas resources in the old oilfields,it is difficult to improve the productivity of oil and gas resources.In order to improve the development effect and recovery of the old oilfield,some adjustment wells were drilled.With the improvement of the development level,the failure rate of cementing in the adjustment block is increasing,and the cementing quality is poor in the later stages of development.At present,in order to improve the recovery rate of crude oil,it is generally used to increase production by means of adjusting the distribution of injection and production wells in the oilfield,adjusting the number of injection and production wells and augmented injection by boost pressure.At the same time,it will increase the porosity of the formation and change the pressure distribution inside the formation,resulting in the underground fluid channeling,which will bring many challenges to cementing operations.In this paper,a detailed study and analysis are carried out on the South Zao block in Dagang oilfield,and the following conclusions can be reached:(1)A detailed study and analysis are made on the geological characteristics of the South Zao block,and the factors affecting the cementing quality are obtained.Because of the long-term fracture acidizing and water flood development,the formation pressure has become very complex,making some formation pressure deficit,and some areas are high pressure,resulting that the high pressure layer,low pressure layer,normal pressure layer at the same time appear in a wellbore profile.Coupled with the effects of long well section and small spacing and the leakage layer,all of those increase the difficulty of cementing operation.(2)According to the formation characteristics of high water in the South Zao block,combined with the existing research results at home and abroad,the experiment will be carried out in the early stage of cement slurry system.The cement slurry system which suitable for South Zao block is put forward:the cement slurry system with short waiting on cement time,early strength and gas channeling prevention at low temperature.(3)The drilling fluid performance adjustment and the design of the balanced pressure in cementing are studied in detail.The method of identifying the water breakthrough in the field is innovated,the pressure test is carried out before cementing to improve the bearing capacity of the wellbore.Through the adjustment of drilling fluid performance,the use of early strength and low temperature,short time cementing and anti-channeling cement slurry system and reasonable design of the slurry column structure,the safety and smooth operation of the whole process of cementing is ensured.The comprehensive measures of this research field practice are carried out and get good application effect.With promoting the technology process,the cementing quality of South Zao block is greatly improved which has important significance on the formulation of other block cementing technology measures.