Dynamic Testing And Evaluation Technology Research Of High Temperature And High Pressure Carbonate Reservoirs In Tahe

Tahe Oilfield is located in the northern part of the Tarim Basin, is China’s first large oil field Paleozoic Ordovician carbonate as the main oil producing zone. The Ordovician oil and gas reservoir is the large carbonate karst vuggy oil and gas layer,reservoir permeability space of the reservoir is composed for different size caves, cracks, dissolution pores and micro-cracks. Due to the cave-fracture distribution in the reservoir is particularly complex, and the reservoir heterogeneity serious, caused by the oil, gas and water relationship is complex, and consists of multiple fracture-cave unit, mutually superimposed on the three-dimensional space of complex oil and gas reservoirs. It also has a deeply buried reservoirs, formation pressure, high temperature special conditions.The description of vuggy carbonate reservoirs and conventional clastic reservoir has a big difference, reservoir understanding and development is extremely difficult, At home and abroad have not yet formed a mature theory and technology. Tahe Oilfield development practices, a lot of research on the development regularity and forecasting methods of vuggy carbonate reservoirs, also made some valuable understanding.Well test analysis technology is an important means of evaluation of oil and gas reservoirs dynamic、completion efficiency and effectiveness of measures, play an important role in the understanding of the reservoir geological characteristics and to determine the parameters of reservoir geology. Domestic scholars have conducted a lot of research of vuggy carbonate reservoirs, and made some positive understanding, played a certain role in guiding reservoir development.Vuggy multi-media widely used test theory model currently, began in the study fractured reservoir seepage regular. In vuggy carbonate reservoirs, reservoir dose not only developed intricate fracture networks, but also developed large-scale dissolution cave. The dual seepage model theory and methods of traditional naturally fractured reservoir, only solve the dual medium model of cracks and pores,it can not solve reservoir media with a large cave. The recent development of numerical well test is more suitable to study the complex formation, and has broad prospects in the field of vuggy reservoir well test interpretation. At home and abroad in the field of vuggy reservoir numerical well test some exploration,but research methods is still a continuum testing model. The discrete media model based on numerical well test method can obtain fracture-cave reservoir network parameters:the degree of seepage network connectivity, the length and penetration of seepage river, the volume of the cave and the distance from the test wells. In particular the volume and connectivity of the large cave has a crucial impact on the state of the oil production, these are not traditional analytical test theory. Vuggy reservoir as a discrete medium to deal more in line with real geological characteristics of the vuggy reservoir, The numerical well test interpretation of the results of the method of discrete media to better reflect the development characteristics of fracture-cave, verified the results of geological interpretation.With the development of the Tahe Oilfield carbonate reservoir, it has formed a series of well test design and data interpretation methods now, but because of the complex nature of the carbonate rocks over the test data to explain the theory of the reservoir model design,reservoir cracks, cave development, conventional model has been difficult to meet the actual production, it is necessary preliminary well test design and data interpretation methods, evaluation, and adaptive analysis; establish the presence of large, discontinuous distribution cave, discontinuous crackdiscrete model of the medium field theory, and consider the true law of motion of the fluid in the cave vuggy reservoir. Interpretation and evaluation of test data need to form a suitable method of Tahe Oilfield vuggy reservoir characteristics, to provide a scientific basis for the efficient development of oil fields.This study is based on literature research at home and abroad, on the basis of summing up the results of previous studies, research Tahe Oilfield carbonate reservoir dynamic evaluation techniques, evaluation of the well test methods and data interpretation problems and adaptability in the past, summary of test datafeature type; through the research of this project, established the vuggy carbonate reservoirs discrete media well test interpretation model of the shut-in pressure recovery and water pressure drop, provided the combination of the cave system parameters, developed vuggy reservoirwell test interpretation software, combined with well test data and production performance data, consummated vuggy reservoir single well well test interpretation, the initial formation of vuggy carbonate reservoirs suitable for Tahe Oilfield dynamic interpretation and evaluation methods. The key findings include:(1) The reservoir space of Tahe Oilfield Ordovician carbonate reservoir is composed by cracks, caves and matrix porosity, the pore-scale has changed dramatically, and has strong heterogeneity, but due to matrixthe physical properties of the system is poor, does not have a set of storage capacity. Therefore, Tahe Oilfield is vuggy reservoir composed of cracks and caverns.(2) Cracks-hole dual media and crack-porosity dual media on the production characteristics are very different, the channeling ability of holes to crack is far greater than the matrix porosity holes to crack, So the fracture-cave medium reservoir does not show dual media feature "concave" characteristics, and cracks-porosity reservoir has a concave display dual media features. The vuggy dual media pore is very similar to a single medium, it can be equivalent to a single medium.(3) Due to the complex nature of the fracture-cave medium pore space, the flow of the discrete medium is composed of the radial flow, linear flow and tank flow. According to the fracture-cave medium with different combinations of the cave, Geological model is divided into2categories and8small class:Round homogeneous formation, round composite formation, circular single-hole formation, linear homogeneous formation, linear composite formation, a linear single hole formation, the linear dumbbell formation, linear beaded strata, and draw their typical curve.(4) The discrete media well test interpretation can not be used analytical method for the continuous medium, it should be used numerical methods, the numerical methods can be used to solved respectively of the radial flow, linear stream, and storage tanks stream, and then get the pressure of feature of the entire flow, further explained that to out of the the geological parameters of the reservoir.(5) Use Delphi2010program prepared vuggy reservoir numerical well test analysis software, explained the5well layer pressure recovery information and pressure drop data, the interpretation of the results in line with actual production.