Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Luo, Ruilan
Evaluation of Dynamic Reserves in Ultra-Deep Naturally Fractured Tight Sandstone Gas Reservoirs
Luo, Ruilan (RIPED, PetroChina) | Yu, Jichen (RIPED, PetroChina) | Wan, Yujin (RIPED, PetroChina) | Liu, Xiaohua (RIPED, PetroChina) | Zhang, Lin (RIPED, PetroChina) | Mei, Qingyan (PetroChina Southwest Oil& Gas Company) | Zhao, Yi (PetroChina Southwest Oil& Gas Company) | Chen, Yingli (PetroChina Southwest Oil& Gas Company)
Abstract Ultra-deep naturally fractured tight sandstone gas reservoirs have the characteristics of tight matrix, natural fractures development, strong heterogeneity and complex gas-water relations. There is strong uncertainty of gas reserves estimation in the early stage for such reservoirs, which brings big challenge to the development design of gas fields. Taking Keshen gas field in Tarim basin as example, during the early development stage, the dynamic reserves were much less than those of proven geologic reserves. As results, the actual production performances are obviously different from those of conceptual design. What are the reasons? How to adjust the development program of gas field? Based on special core analysis, production performance analysis, gas reservoir engineering method, and numerical simulations, influencing factors on evaluation of dynamic reserves for ultra-deep fractured tight sanstone gas reservoirs are analyzed. The results show that rock pore compressibility, recovery percent of gas reserves, gas supply capacity of matrix rock, water invasion are the major factors affecting the evaluation of dynamic reserves. On the basis of above analysis, some suggestions are given for the evaluation of dynamic reserves in Ultra-deep fractured tight sandstone gas reservoirs. For this kind of reservoirs, it is reasonable to determine the gas production scale based on dynamic reserves instead of proven geological reserves.
A Composite Seepage Model for Fractured Reservoir
Feng, Jinde (Research Institute of Petroleum Exploration and Development) | Luo, Ruilan | Cheng, Linsong (China U. of Petroleum) | Chang, Yuwen (Research Institute of Petroleum Exploration and Development) | Yu, Lijun (Research Institute of Petroleum Exploration and Development)
Abstract For fractured low-permeability sandstone reservoir, it is very difficult to use the conventional method to handle the stochastically distributed natural fractures, which do not connected with the wells, in the theoretical study of the naturally fractured reservoir. To study the seepage law of the fractured reservoir, a fractured heterogeneity composite reservoir seepage flow model is proposed by using the equivalent flowing resistance method. With this model, the effects of natural fracture parameters on productivity and formation pressure were investigated. The results indicate that the fractures within 10m to the wellbore will have great impacts on pressure distribution and productivity; and the impacts of fracture length, fracture aperture and fracture number on pressure distribution and productivity will decrease after they are greater than some certain value. The study clarified theoretically the reason that fractures improve the productivity. Introduction The popular method to deal with the hydraulic fracture is conformal mapping, and the hydraulic fracture can be thought as source or sink. The features of natural fractures in the low-permeability reservoir are micro aperture, less length and stochastically distributed in the reservoir and seldom connected with the production or injection wells. By these reasons, it is very difficult to use the conformal mapping method to handle with the fractures. To solve this problem, by assuming that the fractures are not the main reserve media but the seepage channel, which lead to the directivity of formation permeability, and based on the parallel-plane theory, the law of equivalent seepage resistance and equivalent continuous medium theory, a fractured heterogeneity composite reservoir seepage flow model is proposed. The impacts of fracture parameters, such as fracture length, fracture aperture, fracture number, fracture intensity and distance between the fracture and the wellbore, on the pressure distribution and production rate can be investigated by this model. This model is simple and practical with fully considering fracture features. Reservoir Model Considering the fracture features of high angle, definite orientation and the fracture have the best increasing production effects while the streamline paralleling to the fracture orientation, the assumed conditions are as follows:One production well in the center of a round boundary reservoir; The natural fractures are vertical fractures, and their orientations are along the radial direction; Fluid flow follows the Dacy's law, and is single phase and steady state; Reservoir is uniform thickness; The fractures are developed in the local region around the well. The geological model of the fractured reservoir is shown as Fig.1 (a), and the simplified reservoir model is shown as the Fig.1 (b). In fractures developed reservoir, permeability was increased greatly by fractures, so that there is a high permeability region (shown as No.2 region of Fig.1 (b)) in the reservoir. Therefore, the reservoir is divided in to three regions, region 1 and region 3 without fractures, and region 2 with fractures developed.
- Geology > Geological Subdiscipline > Geomechanics (0.78)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.54)
ABSTRACT Because of the favorable properties of CO2, it has been used to enhance the recovery of oil for a long time. But this technology is under slow development in China for lack of rich CO2 resource until some CO2 reservoirs were found in recent years. Using simulation and reservoir-engineering method, this paper presents the feasibility study of CO2 injection for heavy oil reservoirs following cyclic steam stimulation. Pilot tests were conducted to several wells in Lengjiabao heavy oil reservoirs in Liaohe oilfield, China. Some wells got good effect, while some wells got poor effect. And the results from the simulation and field pilot tests are evaluated economically. Study shows that for common heavy oil reservoir after cyclic steam stimulation, the higher the oil viscosity, the greater the CO2 utilization ratio, and the more feasible CO2 stimulation process; for extra-super heavy oil, 1–3 cycles steam huff-n-puff were performed as necessary, followed by CO2 stimulation process so that good benefit could be gained. These results are of significance for field operation and production of heavy oil. Introduction In recent years, many heavy oil reservoirs or blocks in China have entered their late stage of cyclic steam stimulation. With the increasing of steam huff-n-puff cycles, the cost is getting higher and the profit is getting poorer, hence, the development effects are getting worse. The technology of steam huff-n-puff can not meet the needs of heavy oil production. While, there is no mature technology to substitute it. It is necessary to seek new methods to exploit heavy oil reservoirs for which steam stimulateon is not suitable. It has been known for many years that as CO2 dissolves in oil, it swells the oil and reduces oi viscosity. In 1945 Poettmann and Katz discussed phase behavior of CO2 and paraffin systems[1]. They estimate that for a heavy crude there is 10 to 22 percent augmentation in oil volume, and the crude viscosity reduces to less than 0.1 of its original value at 120F(49?) and 800 to 1200 psi (55 to 83 bars) [2]. At lower temperature, the augmentation in volume is greater. In China, CO2 injection technology has been applied to oil production only recently, the major reason being lack of rich CO2 resource. In recent years, some medium and small CO2 reservoirs have been found in Jiangsu oilfield, Shengli oilfield and Jilin oil field, etc. Meanwhile, most of oilfields in east China are entering the late-life production and requiring appropriate EOR technologies. Hence, CO2 injection is becoming more attractive in China. CO2 injection technology has been studied in China since the late 1980's, and pilot tests were conducted in the eastern Sanan of Daqing oilfield, Jiangsu oilfield and Xinli 288 area of Jilin oilfield[3–5] and satisfactory results were obtained. Unfortunately, there has been little study of injection CO2 for heavy oil reservoir in China so far, especially for reservoirs at their late stage of cyclic steam stimulation. For heavy oil, the major EOR mechanisms of CO2 injection are viscosity reduction and volume swelling. Three blocks of Lengjiaobao heavy oil reservoir are selected for our study: block Leng 41, block Leng 42, and block Leng 43. The range of crude oil viscosities of these three blocks varies widely (from 327mPa.s to72700 mPa.s), and several cyclic steam stimulation have been conducted in these three blocks. Several problems exist in the production of these blocks: (1) Back production of injected water is low, which is harmful to improving the effect of steam huff-n-puff at late stage; (2) Wells completed with non-thermal technology can not produce normally using steam injection for more than a few cycles; (3) Oil production is affected by invasion of edge and bottom water in the western edge of blocks; (4)Some wells produce sand.
- Asia > China > Liaoning Province (0.70)
- Asia > China > Jilin Province (0.54)
- Europe > United Kingdom > North Sea > Central North Sea (0.25)
- Asia > China > Heilongjiang Province > Daqing (0.24)
- Asia > China > Shandong > North China Basin > Shengli Field (0.99)
- Asia > China > Liaoning > Bohai Basin > Liaohe Basin > Liaohe Field (0.99)
- Asia > China > Jilin > Yanji Basin > Jilin Field (0.99)
- (3 more...)