Shale gas drilling wells choice

Natural fracture systems that affect the degree of development of shale gas exploitation effective direct factor, so horizontal  shale gas  well locations should be selected in fractured shale region and the high degree of layers, especially where vertical fractures and, apart from the , it should also try to choose organic enrichment, moderate clay content, high brittleness ingredients, Poisson's ratio and Young's modulus lower high places (Figure 1). During operation, usually selected with the main fracture network orientation substantially parallel to the drilling system, this can produce more lateral induced fractures,fracturing proppant so that natural or induced fracture network communicate with each other along the vertical direction of the maximum horizontal stress can increase the wellbore drilling intersects with crack the possibility of increasing the gas flow area, thereby increasing shale gas recovery. Typically, horizontal shale gas wells longer initial production rate and ultimate recovery will be higher, the United States Barnett Shale horizontal section length of 457.20 ~ 1371.60m, according to statistics, the most effective shale gas wells The whipstock and the total length of the horizontal section is generally 914 ~ 1219m.

Drilling in shale formations, the operator faces borehole collapse, torque and drag issues, drilling more difficult than normal, especially in the design completion, which is in the design phase wellbore good question must be considered , wellbore stability and its ability to obtain sustainable yield is essential.

Shale horizontal well completions are openhole completion, the sliding sleeve completion, coiled tubing completions, completions, etc. BHA. Openhole completion late fracturing operations difficult, for  Hydraulic fracturing  techniques are higher, often require hydraulic fracturing and advanced modern technology combined use, such as using a sliding sleeve fracturing, clay content for small wells. Cased hole wellbore stability, when the reservoir reconstruction can selectively perforating, thereby optimizing production operations, casing, after completion, coiled tubing fracturing can be used to transform shale reservoirs. Shale gas wells to use more horizontal wells cased-hole completions. Different completions on drilling technology requirements are different, so the drilling design should pay attention to this factor to consider completions. Shale gas well cementing and segmentation in isolated operation, the operator typically use acid-soluble cement (ASC) as a substitute for conventional cement. Acid soluble conventional cement concrete physical properties and are very similar, but not inhibit the generation of cracks, which in the acid fracturing fluid high solubility (> 90%), easy to remove.