High Quality Downhole Fluids Sampling And Method Study On Dynamic Evaluation For Hydraulic Fracture

Due to formation tester can directly take reservoir fluids sample,it was widely recognized by us.With the shale and tight formation became an important goal of exploration and development,it is facing new demands and challenges for formation tester to take fluid sampling and evaluate hydraulic fracturing.For example,how to quickly draw the virgin fluid from the tight formation? How to amlurately evaluate and identify the formation fluid properties if they are not drawn into the flowline in time? How to effectively evaluate the directional fracturing,etc.It becomes the more and more important priorities for us to figure out the relevant theory,methods,technology,and engineering problems.Amlording to above requirements and challenges,this doctoral paper do a bunch of explorative and innovative research as below.1.The real-time monitoring apparatus,theory,method and its experimental verification for the front fluids of probe in the tight formation.Due to drilling fluids mobility is significantly higher than the one of formation oil,it causes the virgin formation fluids can't been drawn into formation tester in time in the tight formation.But,the fluid analysis module in the formation tester usually determines the fluid properties by monitoring the fluids in the flow line,so it may cause big error.In this study,the formation resistivity is measured in real time in the process of pumping fluid by adding the array electrode on the basis of the existing probe.Through analyzing the resistivity trend of the fluid in the flowline,virgin fluids property is determined correctly to ensure that it is sucked sumlessfully from the formation.Amlording to this design principle,this paper carries on the corresponding numerical simulation and the rock electric relationship experiment by core oil flooding test.Finally,through analyzing the field test data,we verify the correctness and feasibility of the theory.2.The speeding up sucking formation fluids apparatus,method,theory and its verification by electroosmotic flow in the tight formation.In the case of tight formation or deep invasion drilling fluids,the sampling process will be very slow which is caused by low pumping efficiency or high mobility drilling fluids.This study proposed to apply electroosmotic flow technic to speed up virgin formation fluids sampling.On the basis of the existing probe,DC electric field was built by adding a bunch of electrodes on it.Through the theoretical analysis,numerical simulation and core experiments,it is found that the electroosmotic flow excited by the DC electric field can significantly reduce the relative permeability of water and increase the relative permeability of oil.3.The dynamically directional hydraulic fracture evaluation,monitoring apparatus,method,theory and its numerical simulation.In the traditional dual packer hydraulic fracturing job,the hydraulic fluids pressure direction is isotropic.So,the hydraulic fractures are affected by the stress distribution of the original strata,and the direction of the fracturing is difficult to control and predict.In this study,the existing formation tester probe was re-designed into a threedimensional single packer with 16 probes,and the hydraulic fracturing outlet of these probes was designed into a controlled manner.Based on the numerical simulation,the relationship between the generated orientated fracturing angle and the orientated fracturing size by the new three-dimensional single packer was systematically studied.By adding the electrodes on the 16 probes,we can real-time monitor and dynamically evaluate fracture by analyzing the trend of the formation resistivity in the front of probe.Through the above exploratory study,we get below conclusions:1.By monitoring the formation resistivity in the front of the probe,we can quickly estimate the virgin formation fluid properties in the deep invasion.2.Through the external DC electric field excited electroosmotic flow,it can significantly reduce the relative permeability of the water phase and increase the oil relative permeability.3.The novel three-dimensional single packer with 16 probes can perform directional hydraulic fracturing.By monitoring the front of the probes' resistivity,we can evaluate the generated hydraulic fractures in real-time.At the same time,it should be pointed out that this exploration study is based on the existing significant electrical differences between water-based drilling fluid and formation fluid.For the minor electrical property fluids,the research of the theoretical model,forward and inversion method needs to be further studied.