Fourth Department Of The Qinghai Sebei Large Biogenic Gas Gas Field In The Main Development Technologies

Determining the technical method on the development of large gas field formed biologically in quaternary located in Sebei, Qinghai is the main purpose. The key geological problem, which influenced the development of biological gas field in quaternary located in Sebei, Qinghai, was analyzed carefully based on the condition of development geology. According to the successful experience of the development of the gas field at home and abroad, and the production reality in the study area, and using the logging elaborate interpretation software, and the geological model, and the technique of the well testing, these techniques, that is identifying low electric resistance pays, and the elaborate description of gas sand bodies, and the optimizing the grouping of mixed production pays, and the reasonable production distribution for the wells which produce gas in a mixed way, was discussed elaborately. At last, a technique of gas field development was suggested. From the results of filed and laboratory test, the technique is available for the study area.The main research content and innovation of paper was listed as follow:1. Technique of identifying uncertain pays of low electric resistanceAn effective technique of identifying doubtful pays of low electric resistance was founded for those uncertain gas pays which have not clear electric characteristics in Sebei gas field, Qinghai. In order to identify correctly the uncertain pays, three steps must be included. Firstly, Both logging instruments and logging environments should be calibrated, then the strata are processed in standardization. Secondly, Sound wave loggings are not utilized to compose the gas interpretation diagram because sound wave loggings are strongly affected by insufficient formation suppression. Alternatively, in terms of the researches on the Four Characters (resistance, lithology, physical property and oiliness), a method using the cross-links of compensated density logging and resistance logging is utilized to compose the interpretation diagram. Some pays with obvious logging response are distinguished and removed through first interpretation, then, some doubtful pays with low resistance can be identified qualitatively in terms of second interpretation. At last, using the dual-porosity model, which is provided by LOGES logging interpretation system, two parameters of gas saturation and irreducible water saturation are used to help identify the doubtful pays with low resistance. By use of the technique, the proved natural gas geology reserve increased 1.15 times from 2000 to the end of 2003 in Sebei gas field.2. Application of the technique of elaborate description of gas sand bodies According to the characteristics of reservoir deposition, the logging interpretation ofthe parameters such as thickness of net pay, porosity, permeability, gas saturation and siltcontent at every well point in a single sand body, a static parameter field for each sand body and the according database of static parameter model can be set up. Then the gas reserve of each sand body can be calculated. As a result, each sand body can be evaluated and classified qualitatively by weighing every parameter and factor carefully. In the end, the 3-D visible diagram for each sand body can be created using the geological model software. The first use of the technique of elaborate description of gas sand bodies made the sand bodies more clear in distribution and configuration, and made the effective gas development possible.3. Technique of optimizing the grouping of mixed production paysIn light of 3700 series logging data collected from some key wells located in the top structure area in Sebei gas field, a standard profile of logging interpretation can be set up. In addition, according to the FMT continuous logging data, the pressure system unit can be identified. Secondly, numerical simulation is applied to simulate such parameters as moving velocity of edge water, gas production, recovery, stable production time for every pay under different combination of perforation. Also, well points and the location and the boundary condition for each gas sand pay of the wells should be taken into account. This creative use of the technique improved the technique of the gas reservoir development, and made the production stable, and made the recovery efficiency increased.4. Technique of reasonable production distribution for the wells that produce gas in a mixed wayThe reason of sand moving has been analyzes both on site and in laboratory. Many data such as sand sample analysis in laboratory and testing in the field have been collected and analyzed. Based on the principle of Mooree, a correlation model between the natural Gama logging responses for different formations and the critical sanding pressure difference has been created. In terms of the model, the minimum sanding pressure difference in Sebei gas field can be easily calculated, so that a reasonable production pressure difference can be determined when the gas production is distributed. At the same time, in terms of the theory of well testing analysis and the theory of formation sanding, lots of fundamental data from the field are collected and analyzed. Based on the predecessor's achievements, combined closely with practical production situation of the field, mathematical statistics is applied thoroughly in the researches. Finally, a theoretical prediction method of predicting maximum gas production under the condition of non-sanding for the mixed pays production has been put forward.