|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
Jin, Fu (CNPC Engineering Technology R&D Company Ltd.) | Xi, Wang (CNPC Engineering Technology R&D Company Ltd.) | Shunyuan, Zhang (CNPC Engineering Technology R&D Company Ltd.) | Bingshan, Liu (CNPC Engineering Technology R&D Company Ltd.) | Guobin, Yang (CNPC Engineering Technology R&D Company Ltd.) | Yangfan, Lv (CNPC Engineering Technology R&D Company Ltd.) | Haochen, Han (CNPC Engineering Technology R&D Company Ltd.)
It is estimated that low-perm reserves take up 56% total reserves in China, while the combination of horizontal drilling and staged fracturing is the most effective methodology to develop them. However, they are too sensitive to conventional cementation, completion and perforation. Moreover, horizontal intervals are always poorly cemented and the current fracturing techniques may hardly fracture reservoirs by scale. Therefore, innovative cementation and completion technologies are demanded to develop low-perm reservoirs in China.
Based on the classical hydraulic fracturing and rock mechanics theory, two scenarios in which casing joints or tubing strings are respectively used as fracturing strings were compared with each other, in order to reveal the fracturing efficiency and friction loss of fracturing fluids. The casing joint integrated with a pair of external packers, stage collars, several sets of oil-swelling packers, sliding sleeves as well as CT downhole tools such as the mechanic switch and choke valve were also tested indoor and analyzed based on the downhole pipe string mechanics theory.
The wellhead pressure during fracturing may not be reduced until the fracturing fluid friction arising from both boreholes and perforated holes is reduced. The integration of rigless cementation and completion requires taking casing joints directly as fracturing strings, so there is neither perforated hole nor any subsequent friction. In horizontal borehole staged fracturing, the fracturing fluid is injected via the annulus between CT and 5-1/2߱csg., which makes the fluid's flow area more spacious than that of conventional tubing strings. Hence, the fracturing fluid's friction is only 10% of that in conventional fracturing tubing strings. In conclusion, it is feasible to carry out the above integrated design, in which the upper part of the horizontal interval is first isolated by a pair of external expandable packers, and then the stage collar starts to cement the segment above the horizontal interval in order to keep low-perm reservoirs from slurry contaminants. The underneath oil-swelling packers expand in horizontal reservoirs, where a mechanic switch and a wash-over choke valve are RIH via CT to open or close any of the sand preventive sliding sleeves in each reservoir. The fracturing fluid is then selectively injected into corresponding reservoirs to fracture them stage by stage.
As an innovative concept and new trend to develop low-perm reservoirs in China, the integration of rigless cementation and completion requires neither perforation nor drilling. CT is deployed to operate sliding casing sleeves and the fracturing fluid is pumped via casing directly, which greatly improves reservoir stimulation efficiency. There is no fracturing string in the borehole, so no more sand block issue is concerned. Several field trials have been carried out in Missan Oilfield Iraq, showing potential opportunities for low-perm reservoir stimulation.
Lu, Yan (China Oilfield Services Limited) | Wang, Da (China University of Petroleum, Beijing) | Liang, Jiabo (CNOOC Iraq Ltd.) | Feng, Puyong (China Oilfield Services Limited) | Shao, Shangqi (China Oilfield Services Limited) | Wang, Chao (China Oilfield Services Limited)
Matrix acidizing is commonly used to enhance the production of damaged wells. As to undamaged wells, it is commonly believed that matrix acidizing can hardly enhance their productivity or injectivity. In Iraq X Oilfield, the acidizing operations for four undamaged wells have failed to enhance their performances, which seemed to meet this assupmtion.
A novel deep penetrating long wormhole creation acidizing technique has been proposed and tested in X Oilfield to stimulate these undamaged wells. In comparison with averaged acidizing technique, it can create a much deeper dominant wormhole by applying a much larger acid volume and pumping rate so as to further enhance the well's productivity or injectivity. Very important, it applies a new type of solvent that can better remove asphalt from the rock surface to facilitate the rock-acid reaction and a retarded acid system to make sure the acid can go deeper into the formation.
This novel technique has been tested in all of the fore-mentioned three production wells and one injection well, which have been failed by averaged acidizing technique before. For these three production wells, the production enhancement ratio after using averaged acidizing technique was only 7% on average. However, the well test result for one of these wells showed that despite the low production enhancement, the post stimulation skin factor is −2.08, which showed that the near wellbore pollution had already been removed by the average acidizing technique. Then they were treated with deep penetrating acidizing technique and the production increased correspondingly. In addition, for the injection well, after averaged acidizing technique treatment, the injectivity index quickly decreased from 252m3/(d.Mpa) to 95m3/(d.Mpa) in only two months. However, after the deep penetrating technique operation, the injection pressure stabilizes at 0 injection pressure for more than 9 months with the same injection rate.
This new technique has been the first time tried in this porous limestone formation to stimulate undamaged wells after the failure using averaged acidizing technique. Though first tried in this Iraqi Oilfield, it can be extraopolated to other oilfields with similar limestone formation around the world.
High temperatures and wellbore-integrity issues are often encountered when drilling onshore and offshore wells. Formate drilling fluid was initially developed in the 1990s to battle high temperature. Field applications of formate mud have increased since the 2000s. This paper presents worldwide implementations of formate drilling fluid, including field cases in Canada, the North Sea, Germany, the Middle East, and Russia. Experiences with formate mud in Chinese fields that were previously unknown because of the language barrier are also reported. Most field cases reported high rate of penetration (ROP), excellent wellbore stability, good thermal stability, and high production rates upon completion. Reclamation and reuse of formate have significantly improved the cost-effectiveness of formate mud. In the current drilling industry, formate fluid has become one of the best choices for battling high-temperature and wellbore-stability issues.
Gao, Jichao (China Oilfield Services Limited) | Feng, Puyong (China Oilfield Services Limited) | Wang, Da (China Oilfield Services Limited) | Shao, Shangqi (China Oilfield Services Limited) | Cui, Bo (China Oilfield Services Limited) | Wang, Gui (China Oilfield Services Limited)
Matrix acidizing is widely used for removing damage of carbonate reservoirs. In 2017, more than 70 matrix stimulation operations have been conducted in Iraq Missan oilfield. However, for wells with no severe damage and low production performance which are influenced by formation energy decreasing, the effect of conventional matrix is limited. In order to stimulate these wells, a new acidizing technique has been developed which is called large liquid volume deep penetration acidizing.
According to the Darcy Productivity Equation, for carbonate reservoir, decreasing the skin factor below 0 would also increase production even if the skin factor is 0. That is the theoretical basis of large liquid volume deep penetration acidizing. The key points of this method are injection volume and acid system characters. Total injection volume is even twice as large as that of conventional matrix acidification. The acid system should have characteristics such as retarded acid-rock reaction rate and low leakoff coefficient. Viscoelastic surfactant based acid PA-VES and gelled acid PA-GL are used in these works.
In high permeability formation, the viscosity of PA-VES [20 wt% HCL and 8 wt% VES-1] reaches a peak of more than 400 cp at a shear rate of 170 S−1 at 120°C, which would drive acid flowing into tight formation. Other characteristics such as corrosion inhibition, surface tension, inter-surface tension, iron control and sludge prevention have been tested. Gelled acid is widely used because of its economic benefit, its rheology behavior is tested too. During injecting procedure, optimizing the injection rate and choosing large acid volume to produce long effective wormhole in formation, in this way the oil and gas seepage resistance are reduced, deep oil and gas reservoir area is connected, and oil production is improved. 3 wells have been stimulated using this technique in Missan oilfield which achieved the good results.
Large liquid volume deep penetration acidizing still belong to matrix acidizing because of non-fracturing formation. So that this method do not need a rig and would save cost. This paper introduces a novel method to stimulate low formation energy wells and low pollution wells, which is used in Iraq Missan oilfield for the first time.
Is Surfactant Environmentally Safe for Offshore Use and Discharge? The current presentation date and time shown is a TENTATIVE schedule. The final/confirm presentation schedule will be notified/available in February 2019. Designing Cement Jobs for Success - Get It Right the First Time! Connected Reservoir Regions Map Created From Time-Lapse Pressure Data Shows Similarity to Other Reservoir Quality Maps in a Heterogeneous Carbonate Reservoir. X. Du, Y. Jin, X. Wu, U. of Houston; Y. Liu, X. Wu, O. Awan, J. Roth, K.C. See, N. Tognini, Shell Intl.
By International Petroleum Technology Conference (IPTC) Monday, 25 March 0900-1600 hours Instructors: Olivier Dubrule and Lukas Mosser, Imperial College London Deep Learning (DL) is already bringing game-changing applications to the petroleum industry, and this is certainly the beginning of an enduring trend. Many petroleum engineers and geoscientists are interested to know more about DL but are not sure where to start. This one-day course aims to provide this introduction. The first half of the course presents the formalism of Logistic Regression, Neural Networks and Convolutional Neural Networks and some of their applications. Much of the standard terminology used in DL applications is also presented. In the afternoon, the online environment associated with DL is discussed, from Python libraries to software repositories, including useful websites and big datasets. The last part of the course is spent discussing the most promising subsurface applications of DL.
Sun, Nana (Petroleum Engineering College, Xi'an Shiyou University) | Jiang, Huayi (Petroleum Engineering College, Xi'an Shiyou University) | Wang, Yulong (Petroleum Engineering College, Xi'an Shiyou University) | Qi, Aojiang (Petroleum Engineering College, Xi'an Shiyou University)
Summary We consider the emulsion stabilized by organic base and compound surfactants too stable to separate automatically. To obtain an efficient demulsification technique, the influences of microwave-radiation, conventional-heating, and microwave/chemical methods on the demulsification of heavy-oil-in-water (O/W) emulsions were investigated separately. The results showed that as microwaveradiation time increased, the water-separation rate increased initially and then decreased; with increasing microwave-radiation power, the water-separation rate increased sharply first and then increased moderately; and for both microwave and conventional heating, a higher temperature did not imply a better demulsification effect. In addition, the demulsification efficiency was higher and the separated water was clearer by use of the microwave/chemical approach, which needs less demulsifier in a shorter time for O/W emulsion. Introduction With the contradiction between an increase in global-energy consumption and a decline in conventional oil production, heavy crude oils have been presented as a relevant hydrocarbon resource for use in the future. However, the demand for heavy crude oil has been minimal because of its high viscosity and complex composition, which make it difficult to produce, transport, and refine. To be suitable for transportation from reservoir to refinery with conventional pipelines, a favorable pipeline technique is the transport of viscous crude oils as an O/W emulsion (Simon and Poynter 1970; Ahmed et al. 1999). However, it is necessary to realize the demulsification when the emulsion is transported to the pipeline terminal. The demulsification methods that have been proposed by researchers worldwide include the gravitational-sedimentation method, chemical method, electric-demulsification method, ultrasonic-technology method, and microwave-radiation method (Jones et al. 1978; Noik et al. 2006).