全球油田的成熟给石油行业带来了持续的复杂性，该行业在含水量不断增加的情况下寻求具有成本效益的解决方案来重振生产。几乎每一口成熟的常规井都需要某种形式的 EOR 来重建健康的油水比，而油水比不断变化，通常与油田全盛时期的情况发生明显逆转。

当石油产量因油井老化而减慢时，生产商会将水泵入油藏以增加压力，从而增强石油通过地层中各种通道的流动。随着时间的推移，水会找到注入点和油井之间最简单的路径，最终清除该路径中的石油，从而导致产量下降。这就需要采取另一种方法来增加石油流量。

聚合物和碱性表面活性剂聚合物驱，即可溶性聚合物与水混合以增加粘度，长期以来一直被认为是在老化油田实现三次采收的最佳投资回报。聚合物驱中通常使用的物质是高分子量线性阴离子均聚物或共聚物，当水被泵入井下时，它们会将水稠化至约 15 厘泊 (cp)。聚合物增稠的水堵塞了这些容易的通道，迫使水流穿过地层中未开发的部分，以回收原本被困的石油。

这种类型的化学 EOR 一直被业界勉强地追求。主要原因是处理产出的聚合物水以去除悬浮固体（包括腐蚀副产物和沉淀材料，例如硅酸盐和碳酸钙或颗粒）并从水中回收油造成了重大的经济和技术障碍。

由于残留的聚合物碎片，产出水具有较高的粘度，传统的浮选设备无法有效处理，甚至会损害大多数传统的离心分离器。

这些采出水处理应用旨在处理粘度约为 1 cp 的采出水。当聚合物水返回地面时，其稠度比井下泵送时的稠度要低，但仍可具有约5cp的粘度，很容易使设施的效率降低50%以上。水增稠聚合物消除了凝结的能力，凝结使用带阳离子电荷的聚合物来加速油滴和悬浮颗粒从水中的分离。

操作人员使用化学氧化剂来破坏剩余的聚合物并稀释水，降低粘度并允许水得到处理和回收。然而，这种策略意味着剩余的聚合物会丢失，并且必须将额外的聚合物添加回处理过的水中，然后才能重新注入。有价值的返回聚合物的损失意味着聚合物需求量增加 30% 至 50%，从而增加相当大的运营费用。成本效益对于 EOR 作业至关重要，因为水现在是将石油输送到地面的最大支出。鉴于这些问题，生产商通常选择寻求其他三次采油方式，而不是进行昂贵的聚合物驱方案。

无化学处理工艺

一项新技术解决了这一挑战，方法是在水到达表面时去除水中的油和悬浮固体，同时保持大部分或全部残留聚合物完好无损。该工艺的运行不受粘度影响，不使用任何化学品来处理采出水，单程效率为 95%，并且可以将重新注入水中所需的聚合物量减少至少 30%。

减少水处理化学品和聚合物的环境效益和成本节约可能是巨大的。例如，该介质无需建造百万桶沉淀池，以便有足够的时间进行悬浮固体分离。

MYCELX RE-GEN 高级水处理使用可反洗介质来处理采出水和含油废水流，作为去除油和固体的初级或二级处理选项。该介质包含涂有亲油聚合物的无机基材。悬浮固体被介质机械过滤，同时聚合物涂层从通过的流中吸附油。介质是可反冲洗的，因此一旦介质被从采出水中过滤出来的油和颗粒物完全饱和，就会通过将介质擦洗干净油和固体来反转流动，然后将其从系统中去除。然后，干净的再生介质即可用于过滤，并且该过程将重新开始。

这种方法是独特的，因为聚合物可以在反洗过程中再生。使用具有亲油聚合物的粘土的类似水处理技术必须在被油饱和后运输到处置场。该水处理介质可一步去除低至 5 μm 的油和悬浮固体，无需使用化学品。不需要沉淀池或额外的水分离化学品。处理方案可根据进水水质、排放要求和处理后水的最终用途进行设计。对于 EOR 应用，经过介质处理的聚合物和化学负载水可以回收并重新用于注入。由于系统处理产出水而无需氧化增粘聚合物，因此不会出现粘度损失。

聚合物注射回用

先进的水处理介质已在多次成功的试点测试中得到应用，其中包括印度一家主要运营商的一项测试。在北美，该技术从重度乳化采出水中回收了 98% 的含油量，从而能够在成熟的中稠油油田的 EOR 活动中重复使用聚合物注入。在这种情况下，运营商需要对含有 200 ppm 至 2,500 ppm 油和油脂以及 50 ppm 至 100 ppm 固体乳化的采出水进行净化，所有这些都具有不同程度的粘度。客户选择部署 MYCELX 技术来吸引、回收和去除不同浓度的油类型。

EOR 策略涉及聚合物和碱性表面活性剂聚合物驱以提高产量。所得产出水高度乳化，自由水分离出口的油浓度较高。高油位和总悬浮固体浓度升高增加了维持生产水平所需的化学品消耗，降低了工艺效率，并有可能对地层流变学产生负面影响。

事实证明，传统的过滤方法不足以持续将水中的油含量控制在 10 ppm 以下，而这是回收采出水并最大限度地减少聚合物驱过程中化学品使用所需的水平。

为了克服这些问题，该工艺首先在第一阶段使用油/水分离器来回收油，然后在第二阶段使用 MYCELX RE-GEN 先进的水处理介质。这种方法使操作员能够持续从采出水中回收高达 98% 的油，以达到低于 10 ppm 的浓度。先进的水处理介质能够在不破坏残留聚合物的情况下去除悬浮固体并从采出水中回收油，从而可以重复利用水，从而大大节省成本。

通过部署 MYCELX RE-GEN 先进水处理介质，扩大聚合物驱在 EOR 活动中的可行性，为运营商振兴和扩大成熟油井的生产，同时最大限度地提高油田经济效益开辟了新的可能性。

The maturing of the global oil field presents ongoing complications in an industry looking for cost-effective solutions to revitalize production in the face of an ever-increasing water cut. Nearly every mature conventional well requires some form of EOR to reestablish healthy oil/water ratios that are continually changing and often represent a marked reversal of what they were when the field was in its heyday.

When oil production slows down as wells age, producers pump water into the reservoir to increase pressure, enhancing the flow of oil through various pathways in the formation. Over time the water finds the easiest path between the point of injection and the well, ultimately scrubbing that pathway of oil, which results in a decline in production. This necessitates implementation of another means to boost oil flow.

Polymer and alkaline surfactant polymer floods, whereby soluble polymers are blended with the water to increase viscosity, have long been considered the best return on investment for achieving tertiary recovery in aging fields. Substances typically used in polymer floods are high molecular-weight linear anionic homopolymers or copolymers, which thicken the water to around 15 centipoise (cp) as it is pumped downhole. The polymer- thickened water plugs those easy pathways, forcing the flow to find its way through untapped parts of the formation to recover otherwise trapped oil.

This type of chemical EOR has been pursued reluctantly by the industry. The primary reason is that treating produced polymer water for the removal of suspended solids (including corrosion byproducts and precipitated materials such as silicates and calcium carbonates or particulate) and recovering the oil from the water poses significant economic and technical hurdles.

The produced water, which has a higher viscosity due to the remaining polymer fragments, cannot be effectively processed by conventional flotation equipment and even impairs most conventional centrifugal separators.

These produced water treatment applications are designed to treat produced water with a viscosity of about 1 cp. When the polymer water returns to the surface, it is less thick than when it was pumped downhole but can still have a viscosity of about 5 cp, easily reducing the efficiency of the facility by more than 50%. The water-thickening polymers eliminate the ability to implement coagulation, which uses cationically charged polymers to accelerate the separation of oil droplets and suspended particles from water.

Operators have used chemical oxidizers to destroy the remaining polymer and thin out the water, reducing the viscosity and allowing the water to be treated and recovered. That strategy, however, means the remaining polymer is lost, and an additional polymer must be added back into the treated water before it can be reinjected. The loss of the valuable returned polymer means an increase in polymer requirements by 30% to 50%, adding considerable operational expense. Cost-efficiency is critical in EOR operations since water now represents the biggest expense in bringing oil to the surface. In light of these issues, producers often choose to pursue other means of tertiary recovery rather than undertake an expensive polymer flooding campaign.

Chemical-free treatment process

A new technology addresses this challenge by removing oils and suspended solids from the water as it comes to the surface while leaving most or all the residual polymer intact. The process, which functions regardless of viscosity, uses no chemicals to treat the produced water with 95% single-pass efficiency and can reduce the amount of polymer required to be added back into the water for reinjection by at least 30%.

The environmental benefits and cost-savings of reducing water treatment chemicals and polymer can be significant. For example, the media eliminates the need to build million-barrel settling pools to allow sufficient time for suspended solids separation to occur.

The MYCELX RE-GEN advanced water treatment uses a backwashable media to treat produced water and oily wastewater streams, functioning as a primary or secondary treatment option for oil and solids removal. The media comprises an inorganic substrate coated with oleophilic polymer. Suspended solids are mechanically filtered by the media while the polymer coating adsorbs oil from the passing stream. The media is backwashable, so once it becomes fully saturated with oil and particulates that are filtered from the produced water, the flow is reversed by scrubbing the media clean of the oil and solids, which are then removed from the system. The clean regenerated media is then ready for filtration, and the process is restarted.

This approach is unique because the polymers can be regenerated in the backwash process. Similar water treatment technologies that use clays with oleophilic polymers must be transported to a disposal site after being saturated with oil. The water treatment media removes oils and suspended solids down to 5 μm without the use of chemicals in one step. No settling ponds or additional chemicals for water separation are required. The treatment can be designed based on the quality of the influent water, discharge requirements and the end use of the treated water. For EOR applications, polymer and chemically laden water treated with the media can be recycled and reused for injection. There is no viscosity loss since the system treats the produced water without having to oxidize the viscosity-building polymer.

Polymer injection reuse

The advanced water treatment media has been deployed in several successful pilot tests, including one for a major operator in India. In North America the technology recovered 98% of the oil content from heavily emulsified produced water, enabling polymer injection reuse in an EOR campaign in a mature field with medium-heavy oil. In this case, the operator needed to decontaminate the produced water emulsified with 200 parts per million (ppm) to 2,500-ppm oil and grease and 50 ppm to 100 ppm solids, all with varying degrees of viscosity. The customer chose to deploy the MYCELX technology to attract, recover and remove varying concentrations of oil types.

The EOR strategy involved polymer and alkaline surfactant polymer flooding to increase production. The resulting produced water was highly emulsified, with higher concentrations of oil from the freewater-knockout outlet. The high oil levels and elevated concentrations of total suspended solids increased the consumption of chemicals to maintain production levels, reduced process efficiency and risked negatively impacting formation rheology.

Conventional filtration methods proved insufficient in consistently treating the water to less than 10 ppm of oil, which was the level that was required for recycling the produced water and minimizing the use of chemicals during polymer flooding.

To overcome these issues, the process was initiated with an oil/water separator to recover oil in the first stage and was followed by the MYCELX RE-GEN advanced water treatment media for the second stage. This approach allowed the operator to consistently recover up to 98% of the oil from the produced water to achieve concentrations of less than 10 ppm. The advanced water treatment media enabled the removal of suspended solids and the recovery of oil from the produced water without destroying the residual polymer, thus allowing reuse of the water at a major cost savings.

Expanding the viability of polymer flooding in EOR campaigns through the deployment of the MYCELX RE-GEN advanced water treatment media opens new possibilities for operators to revitalize and extend production in mature wells while maximizing field economics.