Effect of drilling fluids on coal permeability: Impact on horizontal wellbore stability

A numerical study on optimization of multilateral horizontal wellbore patterns for coalbed methane production in Southern Shanxi Province, China

“…The study area was a low permeability reservoir (b1 md), and the authors found that lateral spacing (they modeled multiple single leg wells) was a function of permeability and was especially important in low permeability settings. Subsequent studies by Gentzis and others coupled geomechanical modeling and reservoir simulation to examine influence of wellbore stability (Gentzis et al, 2009a(Gentzis et al, , 2009b. Another study compared several different horizontal multilateral patterns, varying spacing, permeability and lateral length using a reservoir simulator and determined optimum lateral spacing, pattern, and well length based on net present value (Maricic et al, 2008).…”

“…Horizontal multilateral wells are capital intensive and careful consideration of stability is imperative to protecting investments. Several researchers have examined wellbore stability based on characteristics of the wellbore (Gentzis, 2009), the mechanical properties of the reservoir (Deisman et al, 2010;Hawkes, 2007;Whittles et al, 2007), and drilling design (Gentzis et al, 2009a(Gentzis et al, , 2009b. However, there is little evidence of work examining probability of wellbore collapse based on the geometry of the drilling pattern alone, which can provide valuable guidance in reservoirs that are highly heterogeneous or poorly characterized.…”

Discrete element model for coal wellbore stability

“…As the world's natural gas demand grows substantially over the next two decades, CBM exploration and development will become increasingly important for ensuring adequate natural gas supplies. To maximize the production of CBM in some complicated geological settings, it is becoming a common practice to drill directional and horizontal wells in coal-beds; because of the special mechanical properties of the often fractured coal, the wells are prone to wellbore instability problems induced by drilling, completion and production operations [1][2][3][4]. Coal-bed is characterized by its natural cleat network, anisotropy with regard to permeability, brittle and mechanically weak property.…”

Research on Transport of Cuttings in Gas Drilling Horizontal Well and Cuttings Falling-prevent Joint Development

“…Gas drilling technology is becoming one of the leading technologies of exploration and development. However, there are still many technical issues required to be solved, such as carrying cuttings [1][2][3][4], wellbore stability [5][6], drill string failure [7][8]. It is very important to study the transport of cuttings in gas drilling horizontal well, which can reveal the transport mechanism of cuttings, present an effective preventive measure and reduce operational risk.…”