The Analysis Of Tectonic Stress Field Direction In Tazhong Area

Tazhong area is located in the central uplift zone of the Tarim.Its total oil and gas resource is more than 5 billion tons and is the key area of the Tarim Basin oil and gas exploration.But owing to the complex geological conditions of having experienced many tectonic movements,Tazhong area is facing great difficulties in the oil and gas exploration.To carry out the study of tectonic stress field is of great significance in the understanding of Tazhong area tectonic evolution,the combination of reservoir characteristics and revealing the distribution rules of oil and gas reservoir mechanism to predict oil and gas zone.The principle of imaging logging method on the analysis of tectonic stress field is generated from the induced joints and the crash down phenomenon of most walls of wells in the drilling process.The data of imaging logging can be used to identify the induced joints and the crash down of walls of wells and to make the occurrence statistics.Generally speaking,the drilling induced joints trend is parallel to the horizontal maximum principal stress direction of today's level;the orientation of wall collapse is parallel to the minimum principal stress direction of today's level.Through the analysis of the geology and tectonic evolution characteristics of Tazhong area,we conclude that Tazhong area is a large nose uplift tilt from southeast to northwest with a characteristic of vertical stratification,north-south zonation and east-west partition in tectonic framework.There are many times of tectonic movements,of which the most significant one is the Caledonian and Hercynian movement.The Tazhong uplift zone are mainly developed in the early Paleozoic and late Paleozoic strata,the geometric plane surface is spread to the north-west and converge in south-east.Interpreting the collected 52 wells imaging logging well data in TaZhong area and making statistics of single well tectonic stress field direction from the 21 wells,outlining the prediction direction map of current TaZhong area tectonic stress field.Fouding that the current tectonic stress field of TaZhong area is in north-east to west-south direction as a whole,some parts have been deflected with EastEast-SouthWestWest and NorthNorthWest-southSouthEast direction.Combining with previous research achievements,considering that Tazhong No.1 fault belt is in the compressive stress as a whole.The stress values showing a tendency to increase gradually from southeast to northwest and the stress near the fault zone is significantly smaller.The South Eastern part is a strike-slip stress field,transiting in NorthWest to a normal faulting stress field.Tazhong No.1 slope-break zone is mostly located in the principal compressive stress field in different geological periods.So,we can deduce that it is a favorable oil and gas area.The paper does the introduction of principle and influencing factors of fault sealing,discusses the impact of stress field of fault sealing.Most the oil and gas reservoirs in Tazhong area are the ancient karst reservoirs.When meet with the cave belt in drilling,there will be abnormal phenomena of accelerated drill,empty drill and borehole collapse.The research results of this thesis can provide important parameters for wellbore stability research,hydraulic fracturing design and reservoir transformation and references for efficient exploration and development of oil and gas in Tazhong area.