Study On Dynamic Monitoring Technology About Formation Pressure-while-drilling

With several years of development and progress of petroleum geology, geologists are increasingly recognizing the importance of the formation pressure. In the oil and gas exploration, researching the cause, distribution and evolution of formation pressure not only help to analyze process of migration and accumulation and the distribution of oil and gas, discover new oil and gas reservoirs, but also help to predict them and reduce or eliminate the security risks in drilling, saving exploration investment. In the oil and gas development, because formation pressure is an important energy to develop oil and gas fields, the level of its value, not only affects the character of the hydrocarbon fluid, but also determines the approach of oil and gas field development, technical characteristics and economic costs of oil and gas exploration, as well as the final harvest rate. Therefore, a gas field, in the exploration stage and throughout the development process, attach great importance to study the basic parameters of formation pressure.Prediction and monitoring for formation pressure is an important factor for oil and gas exploration and development,supply not only relates to whether abnormal pressure exists, but also avoid engineering accident effective during construction.Now, diversified development in oil-gas exploration and development operation makes discriminating oil reservoir, reservoir protection, engineering geological forecasting difficult.On the other hand, With the development of drilling technology, the old fashioned way to measure the pressures can not adapt to new requirements, the parameter do not have well correlations with formation pressure, we urgently need options to solve pressure prediction and monitoring.The technology’s advancements, accuracy, synchronization of Prediction and monitoring for formation pressure has the economic and policy implications, Meanwhile,The developing of future oil gas exploration means new pressure strata get increasing, increases the drilling risk, the demands on the Prediction and monitoring for formation pressure will only get more pressing. At present, the problem of the way of Prediction and monitoring for formation pressure favoring:prediction of formation pressure can greatly raise the accuracy of prediction;a method of formation pressure include limitations; there is no one model pattern matches the modern composite well logs technology to predicting the changes of the pressure of below drilling depth or neighboring layers, and it can not guide drilling operations, ensure salty in drilling effective.This paper summarizes the identifying characteristics of abnormal formation pressure in the aspects of geological, geophysical, logging (engineering, mud, gas measurement), etc. It also explores the calculation methods of formation pressure such us the seismic method, method of drilling, logging method, multi-parameter monitoring methods and studied the prediction methods of formation fracture pressure and collapse pressure. This paper excogitates lithology identification and compaction curve production technology processed by single well logging data, extracts data corresponding slowness segment discrimination based on shale wells for the production of shale compaction curve. By creating compaction curve and calculating formation pressure, it studied development and its spatial distribution of the formation pressure in Dongying Depression, summed up the main causes of abnormal pressure mechanism, the relationship of source rocks evolution and abnormal pressure, and the development of Dongying Depression abnormal pressure evolution model. In the plane, sections and three-dimensional, using Kriging interpolation technique, with the use of statistical predictability, combining with already drilling logs data, stress testing data, drilling and logging date and drill logging data along with drilling, establish formation pressure prediction three-dimensional geological model of Dongying Depression. Software is development is conducted on the basis of it. Functional design is conducted prior to software establishment, including work area management, well management, layer management, stress management model, and carrying out drilling monitoring software requirements analysis algorithms. Designed with the most advanced destination management pattern, starting from the establishment of the work area, and all user actions can be carried out in the work area basemap to enhance the visibility of the software. Nine components modes are used in the development, including single well integrated maps, plans, sections, three-dimensional map, commonly used algorithms, specific algorithms, external data access, data access, and the pressure inside the pre monitoring and control. Plans provides two functions: on the one hand provides support for data management, provides the import, export, and other data quality checking data on the basis of the visualization, on the other hand to provide horizon distribution of different pressure parameter plane in different formation with contours, including: structural layers of flat pressure distribution, pressure layer plane abnormal pressure distribution, etc..Cross section includes predictive wells pressure distribution figure and pressure profile at any point connections. Three-dimensional map display provides an intuitive way for comprehensive analysis and evaluation of a variety of data types of services; single well as a graphical map-based style, to provide a flexible graphical display style and single-well pressure analysis and single-well monitoring.The computer software for pressure prediction before drilling and drilling pressure monitoring introducing in this article, combines block the formation pressure prediction, single well static prediction and real-time monitoring closely together, with comprehensive logging to achieve a pressure prediction and monitoring of automation and real-time, to achieve the scene accurately predict formation pressure. It makes formation pressure prediction and monitoring accuracy of more than 95%, and forecasts the pressure ahead of 10-60m underlying strata, timely discovery of oil and gas layer, effectively guides drilling safety and prevent accidents.This paper combines the sedimentology, petroleum geology, structural geology, logging geology, seismic exploration principle, drilling engineering and computer technology, it has interdisciplinary and leading edge.The following main results have been made by studying the above work:1. Comprehensive analysis of the geology, well logging, drilling data. Present various identification features of abnormal pressure on the basis of a lot of information on the research work. Including parameters drilling, mud, geology and other three categories 21 indicates abnormal formation pressure changes.2. Establish the formation pressure in real-time detection algorithm in the drilling process on the basis of inverse DC Index. With sonic logging method as the standard, combined to pressure testing of production materials build predictive models prior drilling formation pressure, thus establishing the formation pressure monitoring and prediction of the DC mode.3. Establish a multi-parameter monitoring model pre pressure according to the parameters of modern logging site acquired new technology,. Because the number of parameters and types is huge, propose using principal component analysis of pretreatment parameters, and then select the different modeling algorithms, establish and monitor abnormal pressure prediction models.4. According to the feature of the different means of monitoring abnormal formation pressure, establishing DC index of trend line method、the equivalent depth method, Eaton method, the modeling processes of empirical formula of rock strength method, and making calculations takes advantage of the actual data of Dongying Depression.5. Adopting three-dimensional reconstruction and Bedding Kriging technique integrate the data of point, line, plane into pressure three-dimensional, so it will show the distribution of abnormal formation pressure visually.6. According to the feature of comprehensive logging, for the TCP/IP protocol and COM ports, designed and developed the interface to logging instrument, it can flexibly define the label of data Wits, by reference resolve Wits data in common format. It also provides a connection method for real-time database in base, automatically scans the connected computer’s IP address and access port.7. It offers the technology,a variety of models combined, cross-validation of the real-time monitoring formation pressure. In the process of monitoring formation pressure,it is flexible to choose multi-parameter monitoring model, Eaton model, inverse DC index models and so on, the model parameters can be adjusted in real time according to need.8. For the characteristic by abnormal formation pressure of the user group, design and develop a abnormal formation pressure pre-monitoring system. The system has a flexible data input and output functions, manages data conveniently and effectively, edits data in various forms, has many models and methods for selection and three stress analysis, three pressure profile body reconstruction function, drilling real-time analysis and user-defined method functions.9. On the basis of various sub-units partition of Dongying Depression, four sag formation pressure model arc established (Minfeng sag, Boxing sag, Lijin sag, Niuzhuang sag) by the measured and predicted formation pressure distribution. And analyze the various similarities and differences between depression formation pressure and influential factors, carry out a detailed dissection of the Dongying Depression formation pressure from the vertical, the plane.10. Establish model of formation pressure monitoring through five well. There are 3 wells extent consistent with the measured pressure data was 96.3 percent, respectively, Yong930, Fengshen6, Fengshen4; abundance and abundance of deep-six deep four wells; 2 wells followed for 95.18%, Lishen101 and salt222, they are equivalent in the measured formation pressure swing near the density curve, testing the validity of the monitoring model.11. Summarizing each block formation pressure prediction and monitoring, consider that prior formation pressure monitoring, prediction and research of formation pressure distribution is very important. One of the most central is the study of mudstone normal compaction trend of vertical and horizontal distribution, and this will improve the accuracy of forecasting and monitoring the formation pressure plays a key role.The innovation and the characteristics of study of the place are the following:1. Starting from geological conditions, comprehensive logging, seismic and logging and other information, conduct research block pressure, using three-dimensional reconstruction technical-Bedding Kriging technique to establish the mathematical model macroscopic pressure distribution. To the point, line, surface pressure data integration reconstruct a three-dimensional body, visual image to show the distribution of pressure, in order to forecast and monitor drilling provides static prediction models.2. Combining geological research and engineering studies, with multi-disciplinary, multi-information pre-pressure monitoring, precision reached more than 95%, which meets the requirements on oil production. It can be loaded on a comprehensive logging-while-drilling monitoring supporting the use of realization, and can predict certain strata within the lower pressure changes, and improve the drilling process, intelligent systems to solve the urgent need to produce on the field.3. Pressure monitoring software has been established. Loading logging, logging, seismic and geological data simultaneously, linking with comprehensive logging, using multiple parameters pressure prediction, real-time correction, dynamic monitoring and combining prediction with monitoring closely, can reach the purpose of accurately predict pressure. This software development will further improve the logging methods to ensure safe drilling, reservoir interpretation and evaluation to improve accuracy and increase the success rate of logging interpretation. The site is the latest real-time pre-pressure monitoring software systems, can produce good economic returns in oil exploration and development, has great application value.