Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Abstract SMG Microgels are pre-gelled polymers having a narrow size distribution and behaving like large polymer molecules. Their stability is strongly enhanced by internal cross-links. Several SMG microgels having different chemical compositions and cross-link density, with a size of around 2 μm were submited to laboratory corefloodtests. SMG propagation in reservoirs is driven by a size exclusion mechanism. Microgel size prevents invasion of low permeability zones and creates flow resistance in high permeability zones by adsorption on the rock. The permeability cutoff can be tuned by microgel size and chemistry. Permeability reduction generated by SMGs is determined by the thickness of the adsorbed layer which is roughly the size of the microgel in solution. It is little dependent of the adsorption level. Adsorption depends on the chemical composition of the microgel and on the nature of the rock. An SMG Microgel with soft consistency was selected for a Conformance Control field application in a heterogeneous sandstone reservoir. Reservoir permeability ranges between 10 mD and 1200 mD with an average permeability of around 200 mD. The pattern consists of one injection well surrounded by eleven offset producers. The injection lasted 3 months with a total volume of 9,000 m. After a few months, six offset producers showed increase in oil rate along with a reduction of a few points of water cut. One well lost both water and oil, thus proving diversion to the other wells. The trend remains steadily established in the pattern with continuous increase in additional oil production. After two years, more than 33,000 bbl of additional oil has been produced, giving a ratio of less than 0.7 lb of microgel per extra barrel of oil.
Research on Development Rules and Strategies in the Low R/P Ratio of Tarim Major Sandstone Reservoirs
Yu, Lijun (RIPED, Petrochina) | Feng, Jilei (Tarim Oilfield Petrochina) | Zhang, Shuguang (RIPED, Petrochina) | Lian, Zhanggui (Tarim Oilfield Petrochina) | Chang, Yuwen (RIPED, Petrochina) | Feng, Jinde (RIPED, Petrochina) | Yan, Jianwen (RIPED, Petrochina)
Abstract Based on the major Tarim sandstone oil reservoirs, with seven typical reservoirs as the fundamental study units, some relevant researches are conducted, which include changing patterns and their major contributing factors analysis of production decline rate, water content increase rate, ratio of reserve to production (R/P ratio) and balance index of reserve to production. The production decline rate change rules and its major contributing factors have been specifically analyzed quantitatively. It is believed that, comparing with domestic and foreign land reservoirs, the major sandstone reservoirs have made satisfactory progress. After a period of high-yield and stabilized production, the reservoir development has entered a comprehensive adjustment and low yield stage. In the decline stage, the production decline rate is high and the R/P ratio is in a low level. Through the studying of R/P ratio and balance index of reserve to production of different kinds of reservoirs, rational boundary of R/P ratio has been defined, reasonable development system's establishment and technical development policy for 8-to-10-year stable production have been proposed. The research indicates that, multilayer developments, multi-adjustments and pressure maintenance development are all necessary to keep the oil production stable. Through well pattern thickening, injection-structure adjusting and hydro-dynamic method, water-flood recovery can be increased by 8.7%. Thus the major sandstone reservoirs can keep stable production by 2015. However in the long run, the potential of increasing recoverable reserves by water drive is limited. For technological breakthrough in reserve replacement, the author suggests speed up the research and experiment of gas injection method to enhance recovery. These research results have already been applied in the annual plan as well as in the oil field plan for the next five years.
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin > Lunnan Field (0.99)
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin > Hadexun Field (0.99)
- North America > United States > California > Union Oil Field (0.98)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reserves Evaluation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring (1.00)
Abstract This paper presents selected effective technologies and best practices to improve oil recovery from mature fields through waterflooding optimization. These technologies are proved practical, applicable and cost-effective. They can effectively facilitate further development of mature fields, which is more important than ever before in the current economical down-turn environment. First, this paper summarizes and discusses several pragmatic approaches to optimize waterflooding of sandstone reservoirs. These methods have proved to be beneficial for expanding sweep, thus increasing ultimate recovery. Next, the authors introduce two methods to evaluate the effectiveness of application of these technologies, which can support both qualitative evaluation of the successfulness of the applications; and quantitative estimate of incremental recovery. Finally, this paper illustrates the best practices of each waterflooding optimization technology and the associated reservoir dynamic performance. Waterflooding optimization aims at expanding volume sweep to recover bypassed oil in undrained areas or remaining oil in poorly swept areas. The main established approaches include (a) zonal water injection, (b) changing direction of fluid flow, (c) subdividing injection-production unit, (d) water shut-off to improve areal sweeping efficiency, and (e) cyclic water injection. These techniques are particularly applicable to multi-layer, vertically and laterally heterogeneous reservoirs at the high water-cut production stage. One best-practice example shows that converting comingled water injection into zonal injection has successfully arrested production decline, and resulted in an 11.8% incremental recovery. In another reservoir with 98% water cut and 54.5% recovery of changing injection direction by modifying well pattern has led to a 10% incremental recovery by. In still another example, subdivision of injection-production unit combined with infill wells has achieved incremental recovery ranging from 9% to 20%. A further case illustrates that, compared with continuous water injection, cyclic injection had led to reduced water production, lowered water-cut and increased recovery, and resulted in an incremental recovery of 1.84% EUR. To conclude, maximizing reservoir sweep efficiency is the core step of waterflooding optimization. The techniques and best practices discussed in this paper possess both technical and economic viability. Effective application of those methods is an essential part of profitable reservoir management of mature fields.
- North America > United States > Texas (1.00)
- Asia > China (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Texas > East Texas Salt Basin > East Texas Field > Woodbine Formation (0.99)
- Asia > China > Shandong > North China Basin > Shengli Field (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- (3 more...)
Abstract This paper, in part, represents results of a study supported by North Finn, a small oil an gas producer. It includes 13 Muddy Sandstone waterfloods located in the Northern Powder River Basin of Wyoming. The value of the study to the on-going North Carson Muddy Unit Flood is also discussed. Fluvially deposited lower Muddy Sandstone reservoirs of early Cretaceous age have never been successfully flooded in the area. Upper Muddy sandstones deposited in marine dominated environments had varying degrees of success. North Finn's proposed flood was in a lower Muddy, fluvially deposited reservoir. Detailed study of the earlier waterflood failures encouraged North Finn to take certain precautions which have led to the first successful flood of a lower Muddy Sandstone in this area. Introduction In 1989, North Finn, a small independent oil company, was faced with a 65 percent annual primary production decline rate in its North Carson Muddy oilfield, which accounted for more than half of its cash flow. A study of 13 Muddy waterfloods in the area led to the conclusion that four were very successful, three were marginal and six were total failures. A geological analysis of the fields indicated that upper Muddy reservoirs were marginal to very successful while lower Muddy reservoirs were all unsuccessful. The North Carson field produced from the lower Muddy Sandstone. The upper Muddy reservoirs represented several different environments of sand deposition. Sands deposited in a bay head delta-estuarine shoreline environment appeared to flood extremely well while tidal channel deposited sands were marginal waterfloods. The lower Muddy reservoirs were comprised of fluvial channel sands and none had flooded well. Detailed study revealed one very anomoulous field (Oedekoven) which had produced almost 40 percent OOIP before flooding began and only about five percent afterwards. Average primary production for Muddy fields historically had been about 16 percent OOIP. The Oedekoven field directly north of the North Carson field had a salt water disposal well in the down dip water leg of the reservoir prior to unitization and flood. This disposal water was produced from local Muddy fields and was very similar to the water already in the reservoir. The disposal well positively affected production in the nearby wells and appears to have significantly prolonged the life of the field. When the "official" flood began in the field, Fox Hills water, which is relatively fresh and often contains Na2CO3 was used. Fox Hills water was also used in all other Muddy floods in the area. The upper Muddy reservoirs that had been successfully flooded were relatively homogeneous and continuous sand bodies with very little clay content. The unsuccessful floods in the lower Muddy fluvial sand reservoirs were lenticular, heterogeneous sand bodies containing abundant clays. Native water at low rates had little or no adverse effect on the insitu clays. Fox Hills water caused swelling, fines migration, and in some cases, scaling. Pressuring up at the injection wells caused movement of the clays, plugging and finally fracturing. P. 207^
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Wyoming > Wind River Basin > NPR-3 > Muddy Formation (0.99)
- North America > United States > Wyoming > Powder River Basin (0.99)
- North America > United States > Wyoming > Oedekoven Field (0.99)
- (2 more...)
Abstract During the oil and gas development from weakly consolidated sandstone reservoirs, sand production problem is highly prone to occur, resulting in oil production reduction, down-hole tool abrasion and even oil well scrapping. At present, analysis of sand production in oil and gas wells is mainly the prediction of critical down-hole pressure, and there are relatively few studies on the prediction of sand production volume with different practical down-hole pressures. Quantitative prediction of sand production involves elastoplastic behavior of the formation rock and fluid flow within the pores, and it is influenced and controlled by various factors such as mechanical properties of the formation, fluid properties, completion and production technologies. In order to accurately predict the volume of sand production, it is assumed that the weakly consolidated sandstone is a homogeneous isotropic porous elastoplastic medium for which the Mohr-Coulomb criterion is adopted to describe the abrupt strain softening and residual plastic flow. A finite element sand production model has been established for modeling the coupled reservoir matrix mechanical behavior and hydraulic erosion. By comparing with the results of laboratory sand production experiments of weakly consolidated sandstone, the erosion intensity coefficient in the model was determined. Parametric studies have been performed to predict the sand production volume of a realistic oilfield under different conditions. The calculation results show that the borehole diameter of weakly consolidated sandstone is enlarged after erosion for a certain period of time, and there is a change process from rapid sand production, stable sand production to slow down to the trend of no sand production. In the case of high production differential pressure, the total sand production volume is larger than the low production differential pressure. The simulation results can be beneficial for the decision-making of sand production management in weakly consolidated sandstone reservoirs. 1. Introduction The problem of sand production has always been accompanied by the exploitation of oil and natural gas resources. Researchers have been working hard to solve the safety and economic problems caused by sand production for many years.