Combined whipstock and drill retrieval in multilateral drilling
Publication Date: 2014-Jul-22
The IP.com Prior Art Database
During the course of typical multilateral drilling operations, the whipstock would be landed in the latch coupling to provide a means for drilling the lateral leg at a particular depth in a particular direction. A window would then be milled in the casing to provide lateral access. Next, the directional drilling assembly would be RIH to drill the lateral leg of the well, then POOH. The drilling whipstock would then be retrieved from the well. This current method requires 4 trips total (to drill the lateral leg and to retrieve the whipstock). Depending on the depth and complexity of the well, each trip can add several hours to rig time operations. With the high cost of rig times (some rigs are currently operating at $1M per day) extra trips can become prohibitively expensive. These high costs are driving operators to pursue solutions that eliminate trips and therefore make more efficient use of valuable rig time. The purpose of this concept is to provide a method for drilling the lateral leg of the well and retrieving the drilling whipstock using only 2 trips. This equates to a savings of 50% of the time and costs associated with those trips.
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This design is composed of two main subassemblies; the washover assembly and the directional drilling BHA. These sub-assemblies are connected together using what this document refers to as a shear module. The two subassemblies will be tripped into the well while connected at the shear module using a set of shear screws. The washover assembly includes a packer that is used to anchor the washover assembly to the ID of the well at a particular location far enough away from the drilling whipstock to avoid interfering with drilling operations. After the packer is set, weight is set down to shear the screws connecting the directional drilling BHA to the washover assembly, allowing the directional drilling BHA to move freely and drill out the lateral leg. After drilling the lateral leg, the directional drilling assembly is rejoined to the washover assembly at the shear module. The packer is released and the directional drilling BHA and the washover assembly once again move as one unit to washover and retrieve the drilling whipstock. This process is outlined in further detail in the operating procedure section below. Figure 1 shows the components in the complete assembly.
Figure 1. Overall assembly with components
1. Complete standard MLT operations for landing whipstock in latch coupling, milling the window for lateral access, and POOH with milling assembly
2. RIH with washover assembly and directional drilling BHA (attached together as one unit) to recommended depth for washover assembly placement. The recommended depth allows the washover assembly to be placed far enough away from the drilling whipstock to avoid interfering with drilling operations. (see Figure 2).
3. Set washover assembly packer to anchor washover assembly at recommended depth (see Figure 2).
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Figure 2. Recommended depth for Washover Assembly
4. Set down weight to shear the directional drilling BHA from the washover assembly (see Figure 3).
Figure 3. Shear module (light green) threaded into packer (green) and attached to drill pipe (purple) with shear screws.
5. Drill lateral leg to depth per standard procedure
6. Pull directional drilling BHA out of lateral leg into main bore
7. Re-connect directional drilli...