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Properties of Set Aluminate Cement in 600℃ Ultra-High Temperature Xerothermic Environment
Li Xiaojiang, Wang Yueyang, Xiao Jingnan, Wei Haoguang, Yang Ruiyue, Jia Hui
, Available online  
Abstract(27) HTML (12) PDF (2882KB)(2)
Abstract:
The downhole environment in in-situ mining of oil shale is ultra-high temperature and xerothermic, with temperatures above 500℃, which poses a challenge to the sealing integrity of the oil well cement sheath. To deal with this challenge, the performance evolution patterns of set aluminate cement and set sand-containing aluminate cement in a long-term xerothermic environment at 600℃ were evaluated, and the microscopic structural characteristics and changes in hydration products analyzed. The results of the research show that aluminate has a certain inhibitive effect on the decline of the high-temperature strength of the set cement. After aging in a xerothermic environment at 600℃, the strength of the set cement first increases and then slowly decreases. This is because minerals with higher hardness such as corundum replace minerals with lower hardness such as gibbsite. The set cement is mainly in the form of blocky and granular structures, and the structure is still acceptable, but the sizes of the pore throats become larger and the permeability increases. The strength of the set sand-containing aluminate cement is lower than that of the set cement of pure aluminate. After dry heat curing at 600℃, the contents of quartz and corundum increase significantly. The microscopic structural evolution pattern of the set sand-containing aluminate cement is basically the same as that of the set cement of pure aluminate. The degree with which the quartz sand participates in the reaction is low. Although it can partially optimize the pore throat structure of the set cement, its cementation property becomes poorer, and the number of microfractures inside the set cement increases, leading to an increase in permeability. The research results can provide a reference for the development of aluminate cement slurries suitable for high-temperature working conditions in in-situ mining of oil shale etc.
Advances in Deepwater Drilling and Completion Fluid Technology at Domestic and Abroad
Geng Tie, Yang Jie
, Available online  
Abstract(119) HTML (99) PDF (2078KB)(15)
Abstract:
Global deepwater and ultra-deepwater oil and gas resources account for 44% of total reserves, making their development a crucial pillar of energy supply. In recent years, 70% of major new oil and gas discoveries worldwide have originated from deepwater areas. The South China Sea holds abundant deepwater oil and gas resources, and their development is essential for enhancing China's energy self-sufficiency and ensuring national energy security. However, challenges such as high temperature and high pressure, complex geology, hydrate formation, and wellbore stability impose higher demands on deepwater drilling fluid technology. International oil service companies such as Schlumberger, Halliburton, and BP have made breakthroughs in deepwater water-based, synthetic-based, and high-density drilling fluids, which have been widely applied in deepwater blocks such as the Gulf of Mexico and Brazil's pre-salt oil fields. Domestically, China Oilfield Services Limited (COSL) has promoted independent innovation based on multiple oilfields in the South China Sea, developing key technologies such as deepwater hydrate prevention, high-performance water-based drilling fluids, and flat rheology synthetic-based drilling fluids, significantly improving the safety and efficiency of deepwater drilling. This paper reviews recent advancements in deepwater and ultra-deepwater drilling and completion fluid technologies, with a focus on the latest developments in water-based, synthetic-based, and high-density drilling fluid systems, as well as their applications in deepwater oil and gas development, providing a reference for future deepwater drilling and completion fluid technology development.
Preparation of Environmentally Friendly Nano Lithium Magnesium Silicate-Cellulose-Gelatin Composite Gel and Study on its Ability to Control Mud Losses
FAN Yu, TANG Yijia, XIA Lianbin, WANG Rui, HUANG Tao, WANG Jianwei
, Available online  , doi: 10.12358/j.issn.1001-5620.2025.02.008
Abstract(132) HTML (64) PDF (4143KB)(8)
Abstract:
In the context of the global oil exploration and development in the strict implementation of environmental protection regulations, the development of an environmentally friendly and excellent performance of the plugging agent is undoubtedly a highly effective solution to deal with the leakage of drilling wellsIn sol-gel reactions, nano-lithium magnesium silicate (nLMS), hydroxypropyl methyl cellulose (HPMC) and gelatin (Gel) are blended together in a fixed mass ratio. nLMS particles at high temperatures can disperse more evenly in the blend system, and their high specific area promotes their strong adhesion on the surfaces of the Gel\HPMC substrate, these three substances interact with each other through hydrogen bonds and physical entanglement. Through physical-chemical interaction between nLMS and HPMC as well as nLMS and Gel, a hydrogel with highly crosslinked network structure was developed. The hydrogel was then processed by vacuum freeze drying method to produce nLMS-Cellulose-Gelatin particles which were characterized by IR analysis, UV analysis, thermogravimetric analysis, XRD analysis and rheometer measurement. The nLMS-Cellulose-Gelatin particles were measured for their rheological property, plugging performance and pressure bearing capacity in drilling fluids. The results show that nLMS-Cellulose-Gelatin particles have good filtration control property, mud loss control capability, pressure bearing capacity and compatibility with other drilling fluid additives.
Castor Oil-Based Environmentally Friendly Waterborne Polyurethane Filming Agent CWPU
XIAO Fengfeng, YANG Lili, WU Jiale, FENG Shangjiang, QIU Shixin, JIANG Guancheng
, Available online  , doi: 10.12358/j.issn.1001-5620.2025.02.007
Abstract(196) HTML (135) PDF (3794KB)(8)
Abstract:
In the exploration of oil and gas resources, low-permeability oil and gas reservoirs are easily damaged and are difficult to recover. This problem has become more and more serious. The development of filming agents can help solve this problem, however, the raw materials currently used for the synthesis of filming agents are generally petroleum products, which is harmful to environmental protection. As an inexpensive and easily available biomass resource, castor oil is a vegetable oil that exists in nature, with hydroxyl groups in its molecular structure that do not need modification. It also contains a variety of active chemical bonds and can be used to prepare various high-efficiency additives. Isophorone and a chain extender were introduced onto the castor oil molecules to prepare an environmentally friendly waterborne polyurethane filming agent CWPU-1. The particle sizes of this modified product are distributed mainly between 40 nm and 200 nm, and the particles can cover the micro-nano pores and fractures. Observation with AFM shows that the microscopic surfaces of the CWPU-1 particles are continuous and smooth, indicating that CWPU-1 can form a film through adsorption, hydrophobic association and electro-neutralization. This film makes the mud cake more compact and reduces the filtration rate of the drilling fluid. The reduction rates of the filtration at room temperature and after aging at 150℃ for 16 hours can reach 64.7% and 61.1% respectively. The inhibitive property was evaluated with small clay balls. The results show that after being soaked in the drilling fluid treated with CWPU-1 for 6 hours, the mass reduction rate of the clay balls can reach 46%, meaning that the water absorption swelling of the clay balls is inhibited. After being tested with the formation water in a certain area, CWPU-1 does not produce scale. It is thus concluded that CWPU-1 has a good effect on preventing the invasion of drilling fluids and protecting reservoirs from being damaged.
Preparation and Evaluation of a Drilling Fluid Plugging Agent Used in Ultra-Low Temperature Environment in Antarctic Region
ZHANG Guangsheng, LYU Kaihe, SUN Jinsheng, LIU Jingping, SUN Yuanwei, HUANG Ning, YI Haijiang
, Available online  , doi: 10.12358/j.issn.1001-5620.2025.02.006
Abstract(80) HTML (37) PDF (2566KB)(4)
Abstract:
An organic/inorganic hybrid plugging agent GSF has been developed for dealing with the borehole wall destabilization problem encountered in drilling the ultra-low temperature rocks interbedded in the icesheets in Antarctic area. GSF was synthesized using inverse emulsification polymerization method with such raw materials as nano silica, silane coupling agent, methacrylic acid and lauryl methacrylate. Characterization of the molecular structure of GSF with IR spectrometer, laser particle size analyzer and metallurgical microscope showed that GSF has good dispersion performance and good compatibility with other additives in a drilling fluid in −50℃. Increasing the concentration of GSF, the invasion of the drilling fluid filtrate into the sand-bed tester becomes shallower, and the filtration rate of the drilling fluid decreases. At a concentration of 5%, GSF exhibits optimum plugging performance; the depth of invasion by the filtrate is 7.0 cm and the filter loss is 76 mL.
Research and Application Status, Existing Problems and Development Suggestions of Drilling Fluid in China
WANG Zhonghua
, Available online  
Abstract(90) HTML (74) PDF (2240KB)(11)
Abstract:
In response to the need for safe, fast, and efficient drilling, a series of research and applications in drilling fluids have been carried out in China in recent years, and new progress has been made.To facilitate a comprehensive understanding of the current status of drilling fluid technology, promote the continuous standardization of drilling fluid systems, and improve the functionality, performance, and usage level of drilling fluids, this article summarizes the recent research and application of water-based drilling fluids, oil-based drilling fluids and synthetic based drilling fluids,Among them,water-based drilling fluid mainly includes high-performance drilling fluid, ultra-high temperature ultra-high density drilling fluid, foam drilling fluid, environmental protection and reservoir protection drilling fluid,oil based drilling fluids mainly include pure oil-based drilling fluids, water in oil emulsion drilling fluids, and soilless oil-based drilling fluids, synthetic based drilling fluids mainly include Hydrocarbon based synthetic drilling fluids, ester based drilling fluids, and biomass based synthetic drilling fluids, these drilling fluid systems meet the needs of drilling deep and ultra deep wells as well as shale oil and gas horizontal wells.An analysis was conducted on the problems and their causes in the research and application of drilling fluids, And based on the existing problems, propose suggestions for the development of drilling fluid.This review has a certain reference value for the research, application, and standardization of drilling fluids in china.
Formulation Design of Drilling Fluid Loss Control and Plugging Strategies in Deepwater Subsalt Reservoirs
Xu Chengyuan, Zhong Jiangcheng, Zhu Haifeng, Xiang Ming, Lin Zhiqiang, Yang Jie, Chen Jiaxu
, Available online  
Abstract(76) HTML (66) PDF (5300KB)(7)
Abstract:
Subsalt oil and gas resources are abundant worldwide, with significant reserves located in the deepwater offshore regions of Brazil. The Mero field is a typical example of deepwater subsalt oil and gas resources, located in the southeastern Santos Basin offshore Brazil. The reservoir depth exceeds 5000 meters, with an overlying salt gypsum layer ranging from 150 to 3000 meters. The subsalt reservoirs are primarily composed of Lower Cretaceous BVE and ITP carbonate rocks. The Mero3 block in the Mero field experiences the most severe lost circulation, with a total loss of 17,105 m3. Through geological and drilling data analysis, the main causes of lost circulation were identified, including the development of faults and natural fractures, weak formation layers, and the strong heterogeneity of the formation. These factors collectively result in poor pressure-bearing capacity of the sealing layer, leading to repeated lost circulation incidents. This study collected commonly used plugging materials in the Mero field and conducted performance evaluation experiments on particle size distribution, friction coefficient, compressive strength, and compatibility. A database of plugging material performance parameters was established, and high-performance plugging materials suitable for deepwater subsalt reservoir loss prevention and plugging operations were selected. Based on different loss rates, three loss prevention formulas were designed using efficient bridging and dense filling methods, and the application process for these formulas was refined. Furthermore, a strategy for fine-tuning drilling techniques and maintaining a combination of loss prevention and plugging was proposed. This strategy includes strengthening the precise control of the wellbore ECD in loss-prone formations, reducing downhole overpressure, and minimizing the occurrence of induced fractures. The research results achieved significant success in the field plugging operations at the NW8 well of the Mero3 block. In cases with varying loss rates, the plugging strategy effectively slowed down the loss rate. This provides valuable technical support for the oil and gas development of Brazil's Mero field and other similar subsalt reservoirs, promoting the safe and efficient extraction of oil and gas resources.

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