STUDY OF RESIDUAL SOIL SLOPE STABILITY WITH THE APPLICATION OF HORIZONTAL DRAINAGE

This study determines the effectiveness of horizontal drains on a slope which refers to a landslide at Putrajaya, Malaysia, in 2007. The incident buried 27 cars, and about 1200 people were transferred to a safe place. The main cause was identified as continuous and heavy rainfall. In Malaysia, abundant rainfall is common during the wet season. Therefore, one of the remedial measures to improve slope stability is applying horizontal drain to flush out rising groundwater and increase soil strength. In this study, the finite element method package, Plaxis, is used to analyze the slope stability changes in terms of the factor of safety (FOS). The simulation of slope behavior includes the horizontal drain conditions in lowering the groundwater level based on three parameters: the heights, appropriate depth, and inclination angle. The horizontal drains are installed at four different heights of 1 m, 2 m, 8 m, and 28 m from the toe of the slope. Based on the results, the horizontal drain is most efficient to be installed with 15 m long and zero degrees angle at the height of 1 m from the toe of the slope. At 2 m height, the drain should be installed with 26 m long and an angle of 1.8 degrees, and at 8 m height, the drain should be installed with 12 m long and an angle of 4.8 degrees. Moreover, at 28 m, the horizontal drain should be installed 20 m long and at an angle of 8.5 degrees. Therefore, this paper highlights the exceedingly appropriate design of horizontal drains at different heights, lengths, and tilt angles along the slope surface.

The Helical Anchor Type with Application as a Horizontal Drainage Equipment for Slope Protection

Helical anchors, sometimes referred to as screw anchors, screw piles, and helical piles, are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are manufactured using varying sizes of tubular hollow sections for the pile or anchor shaft. This paper presents an innovation of the helical anchor for horizontal drains, a form of subsurface drainage systems for slope protection. To address the adverse effect of groundwater, an expansion of the application of the helical anchor structure in civil engineering is needed, and new drainage solutions are being considered. The features of the helical anchor type for horizontal drainage equipment, analyses of some of its advantages, and conditions of application are presented. Generally, a helical anchor for horizontal drainage is convenient for installation, maintenance, or removal, and is effective for both horizontal drainage and for anchoring the revetment. It is also a typical construction in drainage works, generally performed by a cranking handle or a rotary-percussion-type drilling machine. The helical anchor pipe for horizontal drainage has many segments with joints using a cranking hand for installation and is quite effective where the installation space is narrow or there is no machine. In particular, the installation of this equipment differs significantly from other drilling methods because it can be driven into a sand layer without a hole wall.

Improving 4-1/2" Liner Deploy Ability in 6" Horizontal Hole with Utilization of Improved Characteristics Brines and Friction Reduction Devices

A large operator of a brown field offshore in the middle east has decided to provide full lower Completion accessibility and ensure prevention of open hole collapse as it can lead to various gains throughout the life of the well. Among those benefits, it provides a consolidated well bore for various production logging & stimulation tools to be deployed effectively, as well as full accessibility, conformance control and enable to provide production allocations for each zones. However there are multiple challenges in deploying lower completion liner in drains involving multiple reservoirs and geo steered wells: Well Bore Geometry, dog legs/ tortuosity etc. & differential sticking possibilities and of course the open hole friction. Due to the size of the open hole, restricted casing design and utilization of limited OD pipes further add to the complications of deploying the Lower completion liner in such brown Field wells. This paper intend to review the multi-step methodology approach implemented in recent years by the company to effectively deploy 4-1/2" Liner in 6" Horizontal Open Hole section. Among the techniques used to assist successful deployment of lower completions are: Improving hole cleaning, ensure smooth well bore with the use of directional drilling BHA, reduction of the Open Hole friction by utilizing Lubricated brines, fit for purpose Centralizers, use of drill pipe swivel devices to increase weight available to push the liner & reduce buckling tendency. With the length of open hole laterals reaching up to 10,000 ft for 6" Lower drains, open hole drag, friction & cleanliness are major components that causes challenges in deploying the Liner till TD. The use of specially formulated brines with fixed percentage of lubricants proved to significant reduce friction compared to the drilling mud used for drilling the horizontal drain. The combination of low friction brine with proper centralization / standoff which resulted in reduced contact area with the formation has also shown good results in preventing differentials sticking while running the liner through multilayer reservoirs having significantly different reservoir pressures. Another major constrain to deploy the lower completion liner in this offshore field is the very nature of the wells being primarily workover. This involves generally Tie back liners run to shallow depths to restore the integrity of wells. This limits our ability in the selection of drill pipe that can be used as only smaller OD drill pipes and HWDP can be utilized in order to deploy the Liner to bottom. On many occasions this provides only limited weight to push the Liner down to TD and impact our ability to set the liner top packer. Drill pipe rotating swivel devices have been utilized to improve our weight availability & transferability to push the liner down and to set the liner top packers. In order to provide independent deactivation mechanism for the drill pipe swivel and to have complete success in our liner deployments, a dedicated ball activated sub was designed to deactivate the swivel acting as back up in case primary deactivation methods fails during liner setting. The combined use of all these techniques enabled the company to deploy 4.5" Liners in 6" Horizontal drains with high success in this offshore Brown Oil field of UAE. This resulted in better well construction and complete access to lower drains over the life of the wells.

Substantiation and Selection of Optimal Method of Angren Section Field Drainage

This article describes the results of the timely drainage of the Angren section using the horizontal drains method. It thereby creates favorable conditions for the effective operation of all technological links of the unit, protecting water resources of the area where the section is located using drainage and quarry waters in the national economy.

Reconstruction of the closed horizontal drains in the Jizzakh region

The article is devoted to the reconstruction of existing old drainage systems in order to radically improve the reclamation ecological and sanitary conditions of the lands of the Jizzakh region to improve the social conditions of the population and obtain high stable yields of cotton and other agricultural crops. As a result of many years of theoretical and irrigation to experimental research, operational monitoring in farms in the Pakhtakor district of Jizzakh region. The parameters of the primary horizontal drain are determined based on the analysis of reclamation climatic, soil, geological, hydrogeological, hydrological, economic, and other conditions. The calculation of the reconstruction of horizontal closed drainage is based on the method of A.N. Kostyakov in intensity from working the groundwater level after flushing. The depth of the drainage was determined, taking into account global climate change in recent years; based on these changes, an adjustment was made in the calculations to determine the value of the critical depths of groundwater during the operation of drainage systems. The incoming and outgoing parts of the water balance of the experimental plots were determined. In the presence of pressure groundwater, the size of the supply of groundwater with pressure water is determined. More proposed by the V.N. Shestakov's formula.