Hu, Dandan (Research Inst. of Petroleum Exploration and Development, PetroChina) | Guo, Rui (Research Inst. of Petroleum Exploration and Development, PetroChina) | Feng, Mingsheng (Research Inst. of Petroleum Exploration and Development, PetroChina) | Wang, Liangshan (Research Inst. of Petroleum Exploration and Development, PetroChina) | Wei, Liang (Research Inst. of Petroleum Exploration and Development, PetroChina) | Wu, Yuanbing (Greatwall Drilling Co., CNPC) | Luo, Yupeng (Jidong Oilfield Co., CNPC) | Tian, Ping (Iraqi Co., CNPC)
Y is a giant carbonate oilfield with low permeability and mid-high porosity, of which the characteristic is extensive plane distribution and many series of oil-zones in the longitudinal direction. The service contract required a large scale capacity construction with nearly 30 million ton and long stable production period above 13 years, but provided a low remuneration fee with only 1.4$/bbl. Full oilfield integrated optimization is crucial to achieve high effective development and enhance economic benefit. In this paper, the procedure of research on integrated development optimization was elaborated. The paper established new productivity model with oil-water two phase to accurately evaluate oil well productivity. Depletion mode and zones combination were demonstrated and optimized through core experiments and numerical simulation. The sensitivity studies of well types, well patterns and well spacings were carried out through modelling and empirical formula method. Multifactor analysis was completed with surface engineering and external oil-gas transportation capacity as important factors, and development strategy of rapid productivity construction and rolling development is put forward. Depletion plan for each reservoir has been also optimized based on full reservoir simulation modelling. The recommended depletion plan has been implemented in the oilfield development, of which productivity coincidence rate was nearly 100%, first stage productivity capacity with 5 million ton has been set up in 2012, and IRR increased from 9% to above 13%.
Y is a giant carbonate oilfield in Iraq, with huge oil area, massive geological reserves, multiple zones in the vertical direction, varied characteristics in the lateral direction and high well productivity. These carbonate reservoirs have low natural energy and reservoir pressure declines rapidly when depletion drive is adopted, resulting in low recovery. Development optimization is needed, proper measures should be taken to supplement energy, and economic and effective technical plan should be proposed to improve the production rate within contract period and get a high and stable production. Zones are combined and optimal development mode is selected according to the policy in host country of resources and requirement in production and services contract. The type of well and well pattern is determined based on the underground and surface is integrated and optimized. The goal is to maximize the potential of each reservoir and achieve overall development of the oilfield and improve the production rapidly. The key point in economic and efficient development is to improve well production significantly and keep the well production stable for a relative long period of time, with a low profit of 1.4$/bbld in the contract. In order to improve production by dozens of million tons and get a stable production in the long term in Y oilfield, this paper optimizes the overall development plan to minimize the early investment and to achieve progressive development of the oilfiled and maximize the economic benefit. The production of 5 million tons in the first stage, which was started ahead of schedule, and the productivity of 10 million tons, which was achieved in the second stage, provides references and instruction on how to develop similar huge carbonate oilfield.
Zhao, Limin (PetroChina Co. Ltd) | Liu, He (Research Inst. Petr. Expl/Dev) | Guo, Rui (China Natl. Petroleum Corp.) | Feng, Mingsheng (China Natl. Petroleum Corp.) | Zhang, Zhaowu (PetroChina Co. Ltd.) | Zhang, Yaowen (CNPC) | Wang, Jun (RIPED, PetroChina)
AD oilfield is located in the southeast of Iraq and structurally it is a long axis gentle anticline in Mesoptamian foredeep. This oilfield is in the development planning stage. The accurate formation evaluation plays an important role in making development strategy. In this paper, integrated evaluations of major target formation, Cretaceous carbonate Khasib II were introduced with the combinations of available data.
Khasib II was mainly deposited within marine carbonate platform shoals and distributed stably in the full field with an average thickness of 40m. Based on the core data, four rock types are defined. Upwards lithology varies from planktonic foram micritc wackestone through green algae packstone to bioclastic and calcarenite grainstone. The porosities are almost same, about 25% while permeability varies in a large range for different lithology. Lower Khasib II planktonic foram limestone has no more than 1mD in permeability and no higher than 1ohm.m in resistivity while Upper Khasib II limestones have 10mD in average permeability and high resistivity. Reservoir spaces are mainly pores and vugs while fractures are not developed. Pore types are mainly intragranular pores, intergranular pores and intercrystal pores. Two throat types, the tubular throat and the lamellar throat are identified which are the major control factors for leading to the difference of permeability in lower and upper Khasib II. Test results show that lower planktonic foram limestone is dry and upper limestones produce oil which can be inferred that the low resistivity for lower Khasib II is resulted from the lithology rather than water. Reservoir distribution, petrophysical properties and fluid distribution for upper Khasib II are analyzed.
Hu, Dandan (China Natl. Petroleum Corp.) | Chen, Yuanqian (China Natl. Petroleum Corp.) | Wu, Yuanbing (SINOPEC Company Ltd,) | Zhao, Qingfei (China Natl. Petroleum Corp.) | Feng, Mingsheng (RIPED, PetroChina) | Liu, Hui
Polymer flooding development tests stared from 1990's were carried out on Daqing and Shengli oilfields in China, with water-flooding as its most important development measures formerly, which enlarged size scale of tests continuously. Stable production and enhancing recovery efficiency in these oilfields were implemented by polymer flooding technology. Successful field applications showed the yearly production rate reached to nearly 90 million bbl in Daqing oilfield.
Feasible and effective report has not been provided yet on the problem that the range of recoverable reserves and recovery efficiency can be reached after polymer flooding. Considering most oilfields accomplished polymer flooding in quick succession and some oilfields were just developed by polymer flooding, practical resolution should be recommended such as the corresponding evaluation model for enhancing recovery efficiency range of polymer flooding. The resolution can also provide an evaluation basis of enhancing recovery efficiency for alkaline-surfactant-polymer flooding in future.
This paper proposed an evaluation model for enhancing recovery reserves and recovery efficiency of polymer-flooding based on production decline model of reservoir engineering. Applications of these concepts are illustrated with field examples. Results indicated that recovery efficiency by polymer-flooding after the water-flooding development may be increased between 7% and 12% in Chinese oilfields. The evaluation model has been used effectively to predict EOR effect in Chinese oilfields.