It is the lowest part of the drill string, extending from the bit to the drill pipe. The bha is different depending on whether a mud motor assembly is used as shown in figure 1, or a jetting assembly is used as shown in figure 2. We can bring you significant benefits of directional and horizontal wells whilst drilling underbalanced. Bottom hole assembly bha configurations are often bent in. Pilot hole bottom hole assembly bha based on the geotechnical reports, the soils will consist of primarily sand, silt, and clay with some gravel. It is primary made up of drill collars, stabilizers and the bit. Downhole hydraulic motors, commonly referred to as mud motors.
An analysis of the bottomhole assembly bha in directional drilling. Toro downhole tools toro has taken every precaution as to the accuracy of the content and data presented herein, toro makes no. The bottom hole assembly of the present invention includes a drill bit driven by a positive. Typically though, the bha for a directional hole will incorporate either a down hole motor or a rotary steerable system in order to point, push, or steer the bit in the correct direction. Directional drilling requires specific bha bottom hole. The drillstring means the tubulars and the accessories used to run the drill bit to the bottom. Proper selection of drill string bottomhole assembly for. A sonde is located in the bottom hole assembly bha. Directional bottom hole assemblies drilling operation. When using a steerable assembly in a deviated well it is of course possible to drill the tangent sections of the well with the. The present invention relates to a bottom hole assembly bha for use in directional rotary drilling.
The present invention provides a bottom hole assembly bha for connection to a drillstring for use in directing the path of a drill bit while rotary drilling, the bha comprising a drill bit arrangement 1, means 2 for providing a modified cutting action of the bit in a predetermined portion of the hole during rotation according to according to the rotary position of the bit in the hole. The assembly of drill pipe, sophisticated instruments and pipe called the bottomhole assembly, or bha, is the business end of the drilling rig. The bha is attached to the bottom of a long string of pipe called the drill string. Current directional drilling practice is to drill the greatest portion of a deviated well using rotary bottom hole assemblies. The well was drilled with one run by sustaining an average rop of 37 feet per hour for a total of 10 days. A rotary assembly is designed to increase build or decrease drop the inclination in the vertical plane, and, to a. The bottom hole assembly bha is a portion of the drillstring that affects the trajectory of the bit and, consequently, of the wellbore. Directional drilling is a broad term used to describe any boring that doesnt go in a straight line vertically down. The lower portion of the drillstring, consisting of from the bottom up in a vertical well the bit, bit sub, a mud motor in certain cases, stabilizers, drill collar, heavyweight drillpipe, jarring devices jars and crossovers for various threadforms. At menengai, directional wells are kickedoff with a mud motor in the 12 hole section at a depth of 400m to about 500m. These products are primarily used to land survey tools dropped or run on wireline into the id of the drill string.
Today, the bottom hole assembly serves several useful purposes, in addition to the simple need to effectively load the bit with drill collar weight. Pdf the directional drilling is one of the developed types of the drilling. Factors that determine drilling tendency of the bottom hole assembly bha. Rotary assemblies building assembly, holding assembly and dropping assembly rotary assemblies, as the name suggests, the assemblies which are driven by rotary table at the surface. In casing while drilling, the bottom hole assembly is attached to the casing using a drill lock assembly dla. A non magnetic drill collar may be run above the ocb if the core will be oriented or hole directional read ings are taken. A bottom hole assembly bha is a component of a drilling rig. Bottomhole assembly bha is a complex combination of several drilling tools including directional drilling assembly.
Bottom hole assemblies are located at the lower ends of drill strings, below the drill pipes. It is challenging to drill and case directional well because the bha consists of specialized directional tools such as a bend motor, rotary steerable tools, measuring while drilling tools, etc. The designs to achieve the directional target vary from one well to another depending on the formation being drilled. While the remaining stabilizers hold the bottom drill collar away from the low side of the wall, gravity. The nonmagnetic bottom hole assembly with the steering probe inside is attached to the drill. Directional drilling is common in shale reservoirs because it allows drillers to place the borehole in contact with the most productive reservoir rock. A bottom hole assembly for connection to a drill string for drilling directional wells at buildup. Drilling tools baffle plates help protect bottom hole assembly equipment from damage from objects missed by conventional screens. A method for selecting a bottomhole assembly, including performing a first dynamic simulation of. Horizontal directional drilling plan february 29, 2012. In this type of bottom hole assembly bha a second stabilizer is included at zone1 in order to provide increased drilling bit stabilization against deviation effects of. The bottom hole assembly bha is the component of the drill string that includes the core bit, outer core barrel, various subs, and the drill collars. The proposed approach rests on the use of the key parameter, namely, the stabilizing length of the bottom part of the drill string, which. Rotary steerable system, bottom hole assembly, tripping, orient, nonproductive time, torque abstract one of the main goals while drilling a geothermal well is achieving the minimum drilling cost per unit of energy produced.
Directional drilling is the ability of directing the bit along some predetermined trajectory. It transmits a signal that allows personnel on the surface to track the location of the bha and the drill string as they ride along the design pathway. In the directional hole, weight on bit and the pump rates were increased to maximize the rop. Why bottom hole assembly is critical for drilling rigs. We have included useful information about the rotary shouldered connections pins and. It consists of a string below the drill pipe in a drill string.
Bhapro bottom hole assembly model drilling software. The bottom hole assembly bha is the components used above the bit without taking in consideration the. Using jars during logging operation due to sticking mud or dog legs problem into bottom hole duration. Bhapro is a bottom hole assembly modeling software that calculates the stress and bha components under complex downhole. Drilling engineering a distributed learning course forward the drilling engineering workbook is a correspondence distributed learning course which covers the important elements of drilling a well. A simpler setup is needed for the straight hole, and there is a more complicated assembly for a directional hole. In the modern oil well drilling industry, a typical bottom hole assembly bha always works in harsh downhole environment and must survive severe mechanical and thermal loads. Minimize bit stability problems from vibration, wobbling and jumping. Simple placement of stabilizers in the bottom hole assembly bha can achieve changes in the well deviation, ie, reduce or increase deviation. In recent years, orientationless technology based on a fundamentally new approach to directional wellbore drilling, which consists in proper selection of the drill string bottom hole assembly, is gaining popularity in oil and gas fields of kazakhstan. It is then only necessary to ream the length of the hole equal to the length of the pendulum collars prior to resuming normal drilling. Bottom hole assembly bha design for directional control. Pendulum bottom hole assemblies drilling procedures.
Bottom hole assembly for directional drilling anadrill. The bottom hole assembly is the crucial component to the drilling rig. Nrv shall be installed in all bottom hole assemblies which are used in top hole drilling in order to prevent uncontrollable flow up the drillstring. Introduction to bottom hole assembly bha post a comment. Bottom hole assembly downhole motors downhole mechanical cutting action required for harder soils is provided by downhole hydraulic motors. Antech provides a complete directional coiled tubing drilling dctd service using its proprietary colt and polaris bottom hole assemblies bhas. Bottom hole assembly for directional drilling halliburton energy. Us5857531a bottom hole assembly for directional drilling. Coiled tubing drilling service antech ltd directional. A typical assembly consists of a drill bit, collars, and various other items such as mud motors. A this drilling motor handbook is for informational purposes only. A conventional rotary drilling assembly is normally used when drilling a vertical well, or the vertical or tangent sections of a deviated well. The bottomhole assembly must provide force for the bit to break the rock weight on bit, survive a hostile mechanical environment and. Different setups are required according to the complexity of the well trajectory.
The emphasis is on the theory behind these drilling elements in order to develop a greater understanding of the principles involved in drilling a. Pdf implementation of a bottomhole assembly program. Directional drilling an overview sciencedirect topics. Bottom hole assemblies bottom hole assemblies introductory comments on bottom hole assemblies the title of this publication is drilling assembly handbook and most of the pages are devoted to the entire drilling assembly, from the swivel to the bit. Nonmagnetic bha components to reduce the magnetic interference by steel components, nonmagnetic drill collars andor. Drilling bha types used in oilfield drilling operation. The designs to achieve the directional target vary from one. Bottom hole assembly bha design for directional control petrowiki. The drill string is composed of drill pipe, heavy weight drill pipe, drill collars and other components like stabilizers and drilling jars. The bit was run more hours and would have run additional time but encountered problems holding direction. The bottom hole assembly of the present invention includes a drill bit driven by a positive displacement drilling motor, the motor being constructed of tubular housings, one of said housings having a bend so as to cause the bit to drill directionally, another housing containing a rotor and stator to generate power, and a flexible section between the power generation housing and the bend. Some basic equations for predicting the performance of.
The horizontal directional drilling process the tools and techniques used in the horizontal directional drilling hdd process are an. A directional bottom hole assembly has almost an infinite number of layouts depending on what targets are required and what tools will be incorporated. For a drill of this length, with a pull back of 10 inch hdpe pipe, the anticipated schedule is set. Appendix c hdd construction plan hdd contingency plan. The assembly can consist of drill collars, subs such as stabilizers, reamers, shocks, hole openers, and the bit sub and bit. It is at this point that the directional company arrives at the drilling rig location. This bottom hole assembly bha is used for formations which have medium crooked hole tendency such as medium and soft formations. It is intended to be an aid to the operator and is provided for information and illustration purposes only. The modeling of the bottomhole assembly bha is an essential prob lem in directional drilling. Preliminarily we have chosen to assemble the bottom hole assembly bha as follows. Actually these are the bottom hole assemblies bhas designed to drill a well directionally build or hold or drop without the use of downhole motors. Read more its a common practice to be told you running an additional tool on top of your bha or in your bha, though the tool may not be a part of your bha, but knowing the function of the tool. Directional bottom hole assemblies directional bottom hole assemblies.
Directional drilling is common practice in shale gas plays such as the bakken and barnett shale, and the selection of drilling tools is critical. Bottom hole assembly bha design, drill string design, torque and drag analysis, as well as. Directional well design, torque and drag limitations, hydraulics and hole cleaning, vibration and wellbore stability, equivalent circulation density. In fact, even in a vertical well, it might be necessary to deviate to avoid a geological formation or a previous stuck pipe, then return to the original path. The hdd bottom hole assembly bha in drilling hdd projects, the away portion of the downhole drillstring just above the bit is called the bottom hole assembly bha. Minimize directional control problems by providing stiffness to the bottom hole assembly bha.
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