There are not only wide distribution, great thickness and various types of Marine carbonate rocks of Lower Triassic in Feixianguan Formation in the northeast Sichuan basin, but also many periods of evolution which involve the diagenesis and tectonism, the rocks have evolved into bank facies dolomite reservoir with excellent reservoir property. Based on the study of the sedimentaiotn, diagenesis, tectonic burial history and the heat evolution of organic matter, the authors research the dissolution which is very important to the development and evolution of reservoirs in Feixianguan Formation in the northeast Sichuan. According to the dissolution characteristics and geochemical characteristics of chemical fillers, four stages of dissolution are identified, they are quasisyngenesis stage, liquid hydrocarbon stage, gaseous hydrocarbon stage and structure lifting stage, and then the forming mechanism of dissolution of different periods is further studied. At last, a model of the burial dissolution at liquid and gaseous hydrocarbon stage is proposed and the influence of dissolution on reservoirs concluded.
According to the geochemistry, sedimentology, lithology, the dolostone in Feixianguan Formation in lower Triassic series, northeast Sichuan is studied in terms of geochemistry and lithology, it is pointed out there are two kinds of dolomization in Feixianguan Formation, they are mixedwater and seepagereflux dolomitization. Oolitic dolostone formed by mixedwater dolomitization distributes along platform edge in the shape of band. Gypsiferous microcrystal dolostone and dolarenite formed by seepagereflux dolomitization distributes planarly in lagoon. Distribution research of dolomitization is made, and next exploration target is pointed out.
The exploration practice in Sichuan Basin demonstrates that the reservoirs in Feixianguan Formation, lower Triassic are the porous bodies developed at the background of large area tight rocks, and related to beach facies, in general, there is a tendency of belt and sheetshaped distribution with strong heterogeneity partially. On the basis of comprehensive geologic research, the seismic prospecting technology of lower Triassic reservoir is summarized and improved, the available seismic data are fully employed, the traditional seismic facies identification technology used in oolitic reservoirs, Feixianguan Formation is further completed, reservoir prospecting research is conducted and a set of traditional seismic identification technology suitable for KaijiangLiangping Trough is explored.
Some gas reservoirs with high H2S content have been found in northeast Sichuan in China, such as PuGuang gas field, Luojiazhai gas field and so on. In the course of development of the gas reservoirs with high H2S content, as formation pressure falls continually, elemental sulfur will precipitate from gas phase after running up to critical saturation state and deposit at reservoir pore space and throat, consequently resulting in formation porosity and permeability reduction; gas well production halts when it becomes severe. Gas reservoirs with high H2S content sulfur deposition prediction model is set up according to dissolution mechanism of sulfur in nature gas and material balance theory and the Luo7 well taken as an example to forecast sulfurbearing saturation in different pressure range, as well as effect of sulfur deposition on production rate. Achievements show that，when gas reservoir pressure drops down to 40 MPa ，production rate falls by 82.5％;reservoir pressure drops down to 37 MPa，gas well production will halts.
The productivity in Luojiazhai gas reservoir is analyzed and forecasted according to its reservoir characteristic, the result shows that, to single well productivity forecasting, the superiority, duration and practical application of the new approach of transient well test based on coupling gas reservoir and well bore can not only be used to forecast by directly employing transient pressure test data, also, by determining formation parameters through production dynamic data matching, meanwhile, it can be used to study the different work procedure, the way of well completion and productivity change under the condition of improving EOR. The approach provides a advanced means to oil reservoir engineering research of depletion recovery.
Mudstone is a kind of clastic rock, which possesses pores and porosity, there is also permeability, but its permeability is quite poor due to the extremely small openness of pores. Mudstone can definitely transport water with poor permeability. Oil wells usually produce a little quantity of water at beginning of production, which comes from the mudstones lying over and under the reservoirs, not the formation water dissolved in crude oil. The abnormal pressure in formations is resulted from the geological accidents, and is a temporary status of pressure, which is so far not balanced by water transportation in mudstones during short time.
Luo ping-ya, male, Han nationality, a Communist Party member, was born in July 1940 in Changlong Sichuang Province. Professor, the tutor of doctor, the academician of the Chinese Academy of Engineering, the Former President of Southwest Petroleum University, the Former Director of the Academic Committee in the State Key Laboratory of "Oil and Gas Reservoir Geology and Exploitation" . For the past 40 years, he has been committed to the teaching and research on the exploration and exploitation of Oil and Gas and has Obtained lots of great achievements on fields such as, drilling and completion fluid technique, reservoir protection technique, theory and application technique on oilfield chemistry. These achievements are mainly summarized as follows: First, study on deep wells drilling fluid with high temperature resistance: In the mid-1970s, he proposed to improve the performance of the mud taking the advantage of high temperature and established the new ultra-deep mud system (anti-high temperature sulfonated mud system) of "the more deep the well, the higher the temperature, the longer the action time, the better the performance, the more simple the process, the lower the cost " , providing the necessary technical support for the success of deep well drilling. This system is still the main component of deep well mud technology in China and has been widely used.Second, Polymer Mud Technology: During the 1980s, he advanced that amphoteric polymers can be used for drilling mud agent and developed a series of new polymer treating agents and matching technology, which is one of the main components and development direction and is still being widely used. Third, Drilling and Completion fluid technique for reservoir protection: He proposed the point of shielding temporary plugging technique for reservoir protection and developed matching technology series, which solved the reservoir protection problems when drilling in oil layers using drilling fluid under positive pressure gradient and made great economic and social benefits. This technology is still being widely used. Fourth, the development of water-soluble polymer with heat and salinity tolerance, anti-shearing, efficient and viscosified: It provides the necessary theoretical basis and material guarantee for the establishment of various of displacement fluid system which is suit for enhancing recovery by chemical flooding in China.Besides, he also obtained great achievements on hole stabilization, horizontal drilling technology, oil-displacement mechanism by chemical flooding, application of seepage of physical chemistry, reservoir protection technology during oil production, Theory and Application Techniques of oilfield applied chemistry engineering and so on.He has presented and accomplished more than 40 research tasks belonging to Ministerial and provincial levels and obtained more than 30 awards of science and technology (including excellent teaching achievements) of which include 7 national awards and 13 Ministerial and Provincial Level awards( of which 3 are rated as CNPC ten annual excellent results ) and published 6 works and more than 100 papers, as well as cultivated more than 90 masters and doctors.Since he has obtained series of outstanding achievements both in scientific research and teaching, he is commended 6 times by government and rated as model worker and advanced teacher belonging to Ministerial and Provincial Level. He was granted as A NATIONAL JUNIOR EXPERT OF OUSTANDING CONTRIBUTION in 1986 and was approved AN EXPERT ENJOYING SPECIAL GOVERNMENT ALLOWANCE in 1990. He obtained Sun Yue-qi Energy Award in 1993 and became the academician of the Chinese Academy of Engineering in 1995. He is also the member of the third and fourth subject review groups of the State Council High Degree Committee, the member of High Degree Committee in Sichuan province, deputy to the sixth and seventh NPC, deputy to the sixth Sichuan provincial Party Congress and the 2000th national advanced worker.
