Water-control for horizontal wells is a worldwide problem, while it is even harder for limestone reservoir because of the developed fractures and caves.

The formation water can be connected to the wellbore by fractures or caves directly or indirectly. Make the wells easily water flooded.

Segmented water-control is the consensus of the current mainstream mechanical water-control technologies for horizontal wells, the segments confine the water break-through influence scope to the segment where the water break-through formed. In order to achieve that, all the potential water break-through fractures and caves connected to wellbore should be concentratedly divided into less segments, but that depends on the distribution of fractures and caves. Otherwise, the number and the sealing location of the packers are also relying on the engineering technology and the well status.

Fracture/cave axial channeling inside the formation is another problem. The fractures and caves interwoven inside the formation. The formation water can easily flow around the packers by fractures/caves and cause the sealing failure of packers and invalid segment.

Meanwhile the conventional mechanical water-control methods have no ability to limit the flow conductivity of fractures and caves. In the segments with fractures/caves developed, the producing degree of the matrix will be low.

As a result, the application effect of conventional water-control methods in limestone reservoir horizontal wells is limited.

To conquer the fracture/cave channeling and achieve the water-control effect at the meantime, the article proposed a novel mechanical water-control method which combined particle-filling with inflow control device screens. The particle-filling is not an absolute sealing, but a limitation of flow rate in the pack area. Calculations show that the flow conductivity of a 5 mm fracture will decreased to 0.1% of the original after particle-filling. The particles filled into the annulus between the screens and the borehole wall can limit the axial annulus flow enormously, replaces the traditional packer sealing. The particles filled into the fractures will reduce the flow conductivity sharply, and no need to concern about the channeling inside the fractures and caves interwoven. Inflow-control devices are utilized to control radius flow rate and balance the production profile near well. The novel water-control method obtained the outstanding application results especially in the limestone reservoir, with the function of deep production profile control combined with wellbore water control, has the advantage of both chemical water shut-off and mechanical water-control methods.

Successful application in reef limestone reservoir demonstrates the excellent feasibility of this novel water-control method. The oil rate increased 3.9 times after application to well A4A in Liuhua oil field South China Sea. For well A3, the initial water-cut is only one third of the average value compared with wells drilled in recent years at the same layer.

It is found that the production effect of oil wells is positively correlated with overfilling amount. For higher overfilling amount, filling process optimization is carried out, and micro-fracturing is formed by increasing filling rate to the target reservoir. The max filling rate of oil well reached 292% by the improvement of filling technology.

水平井控水是世界性难题，而石灰岩储层裂缝、溶洞发育则更加困难。

地层水可以通过裂缝或洞穴直接或间接地与井筒相连。使水井容易被水淹没。

分段控水是目前主流水平井机械控水技术的共识，分段将水突破的影响范围限定在形成水突破的段。为实现这一目标，应将所有与井筒相连的潜在水突破裂缝和洞穴集中划分为较少的段，但这取决于裂缝和洞穴的分布情况。否则，封隔器的数量和封堵位置也取决于工程技术和井况。

地层内部的裂缝/洞穴轴向窜流是另一个问题。裂缝和洞穴在地层内部交织。地层水很容易通过裂缝/洞穴在封隔器周围流动，造成封隔器密封失效和无效管段。

同时，传统的机械控水方法无法限制裂缝和洞穴的导流能力。在缝洞发育段，基质的生产程度较低。

因此，常规控水方法在石灰岩储层水平井中的应用效果有限。

为克服缝洞窜水，同时达到控水效果，提出了颗粒充填与控水装置筛网相结合的新型机械控水方法。颗粒填充不是绝对的密封，而是填充区域内流速的限制。计算表明，5 mm裂缝的导流能力在颗粒填充后将下降到原来的0.1%。填充在筛管和井壁之间的环空的颗粒可以极大地限制轴向环空流动，取代了传统的封隔器密封。颗粒充填到裂缝中会大幅降低导流能力，无需担心裂缝和洞穴交织内的窜动。流入控制装置用于控制半径流量和平衡井附近的生产剖面。新型控水方法取得了突出的应用效果，尤其是在石灰岩油藏中，具有深部生产调剖与井筒控水相结合的功能，兼具化学堵水和机械控水两种方法的优势。

在礁灰岩储层中的成功应用证明了这种新型控水方法的良好可行性。应用于南海流花油田A4A井后，增油率提高了3.9倍。A3井与近年同层钻井相比，初始含水量仅为平均值的三分之一。

发现油井的生产效果与超注量呈正相关。对于较高的超充量，进行充填工艺优化，通过提高对目标储层的充填率形成微压裂。通过充填技术的改进，油井最大充填率达到292%。