Study On The Diagnosis And Production Technology Of Low And Low Efficiency In W Oilfield

W oilfield, with large layer thickness in the major three sections; strong in reservoir heterogeneity; complex in injection-production well network connectivity and severe formation damage, quite a few wells are produced at low production rate, effecting the development adversely. Since the damage mechanism hasn’t been studied clearly, there are no effective countermeasures. In order to address the current problems and provide reference for other oilfields, the reasons for low production and efficiency were studied in depth based on literature review, static and dynamic experiments and mathematical simulation. The following achievement and recognition can be made:1. Based on the pervious geological research achievement and combined the production characteristics, the reasons for low production and efficiency were studied according to the reservoir condition and production process, which provided basic foundation for the genetic diagnosis of low production and the selection of stimulation technologies.2. Based on the actual production situation, the reservoir damage types damage mechanrsm and regularity were studied under simulated formation temperature and pressure. Both macro and micro analysis such as dynamic displacement, SEM scan, X-ray diffraction energy spectrum analysis were involved in this process. Test results indicated:(1) Calcium phosphate was found to precipitate as a result of incompatibility of drilling fluid with perforating fluid;(2) With rapid changes in temperature (during the operation process), the changes in crude oil properties can easily cause the sediment of organic matter, causing the wettability change of rock surface and reducing the flow capacity;(3) Strong particle migration was found in the reservoir, the velocity mutation in near wellbore area can result in formation damage;(4) The formation tendency of crude oil emulsion was found under the following condition:weak acid, weak alkali, particle migration and inorganic scale, crude oil was therefore emulsified and the damage can be severe even with tiny viscosity change;(5) Formation water had scaling tendency under the reservoir condition, and the scaling tendency was also found at arbitrary proportion with seawater.3. On the basis of reservoir geological characteristics, damage mechanism and inefficient reasons, a strong adaptive learning and nonlinear mapping ability method, BP neural network system, was put forward to diagnose the main causes on inefficient. The main reason of low efficiency of typical wells in W oilfield was determined, thus provide scientific basis for optimizing design scheme to increase production.4. According to the genetic diagnosis of low efficiency in W oilfield, appropriate production technology and the corresponding working fluid system were raised to remove formation damage, water control and production incremental. The enhanced recovery technique characteristics, wellbore conditions and offshore operation environment were taken into consideration. The research content and achievements obtained in this paper can provide strong theoretical and technical support for low efficiency wells in W oilfield, and in the meanwhile, provide research methods and technical ideas for oilfields with similar low efficiency issues.