Formation Pressure Inversion Method Based on Multisource Information

Abstract

Summary The exploration and development of offshore oil and gas have greatly alleviated the tension of global oil and gas resources. However, the abnormal pressure of offshore reservoirs is more common compared with terrestrial oil and gas reservoirs, and the marine geological structure is complex, with the development of faults, fractures, and high and steep structures, which leads to the strong anisotropy of formation pore pressure distribution and uncertainty of pressure system change. In this paper, considering the corresponding characteristics of the randomness of the formation pressure prediction results in the Eaton equation for their respective variables, a formation pressure inversion method based on multisource information, such as predrilling data, bottomhole while drilling data, seabed measured data, and surface measured data, is established. On this basis, combined with the data of a well in the South China Sea, the variation law of the uncertainty of formation pressure prediction results under the conditions of predrilling data, measurement while drilling (MWD) data, and their mutual coupling is analyzed. The simulation results show that the uncertainty distribution of formation pressure prediction based solely on predrilling data shows linear accumulation trend with well depth, and the formation pressure inversion method based on multisource information can significantly curb the increasing trend of uncertainty when MWD data are introduced. Therefore, through the analysis of typical change patterns of monitoring parameters under normal/abnormal conditions during drilling, combined with the method of multisource information, the abnormal pressure information can be accurately predicted and inversed, which provides important support for wellbore pressure regulation under complex formation conditions.

Determining the drilling mud window by integration of geostatistics, intelligent, and conditional programming models in an Oilfield of SW Iran

“…They assumed that the minimum injection pressure to hold open and extend a fracture is equal to the minimum stress. Later on, many empirical and theoretical Equations and applications for fracture gradient prediction were presented (Aadnoy and Larsen 1989;Althaus 1975;Anderson et al 1973;Breckels and van Eekelen 1982;Constant and Bourgoyne 1988;Daines 1982;Eaton 1969;Fredrich et al 2007;Haimson and Fairhurst 1967;Keaney et al 2010;Matthews and Kelly 1967;Oriji and Ogbonna 2012;Pilkington 1978;Saadatnia et al 2022;Wessling et al 2009;Zhang 2011;Zhang et al 2022). In this study some commonly used methods are described in the following sections.…”

“…The pressure of the drilling mud will cause a tensile failure in the wellbore, and drilling mud will be lost in the formation of the MW applied higher than the safe mud window. Shear failure or breakout will occur while this weight is applied lower than the safe mud window (Baouche et al 2022;Darvishpour et al 2019;Le and Rasouli 2012;Zhang 2013;Zhang 2019;Zhang et al 2022;Zoback et al 2003). If geomechanical parameters are unavailable, the equivalent MW is calculated using a confidence interval called a safety margin of about ±200 pounds per square inch (PSI).…”

Determining the drilling mud window by integration of geostatistics, intelligent, and conditional programming models in an oilfield of SW Iran

“…They assumed that the minimum injection pressure to hold open and extend a fracture is equal to the minimum stress. Later on, many empirical and theoretical equations and applications for fracture gradient prediction were presented (Aadnoy and Larsen 1989;Althaus 1975;Anderson et al 1973;Breckels and van Eekelen 1982;Constant and Bourgoyne 1988;Daines 1982;Eaton 1969;Fredrich et al 2007;Haimson and Fairhurst 1967;Keaney et al 2010;Matthews and Kelly 1967;Oriji and Ogbonna 2012;Pilkington 1978;Saadatnia et al 2022;Wessling et al 2009;Zhang 2011;Zhang et al 2022).…”

“…The pressure of the drilling mud will cause a tensile failure in the wellbore, and drilling mud will be lost in the formation of the MW applied higher than the safe mud window. Shear failure or breakout will occur while this weight is applied lower than the safe mud window (Baouche et al 2022;Darvishpour et al 2019; Le and Rasouli 2012;Zhang 2013Zhang , 2019Zhang et al 2022;Zoback et al 2003). If geomechanical parameters are unavailable, the equivalent MW is calculated using a confidence interval called a safety margin of about ± 200 pounds per square inch (PSI).…”

Application of Pressure-Volume (P-V) Fractal Models in Modeling Formation Pressure and Drilling Fluid Determination in an Oilfield of Sw Iran

“…To calculate the effective pressure in the reservoir area using the Bowers relation, the relation coe cients must rst be obtained. Thus, according to the effective pressure information at wells (MDT/RFT/DST) and the overburden pressure cube created in the previous section, the effective stress at points of these wells can be calculated [19][20][21][22][23].…”