Modeling research on the extreme hydraulic extension length of horizontal well: impact of formation properties, drilling bit and cutting parameters

Abstract

Horizontal well can increase well productivity and improve the economic benefit, which significantly promotes the development of shale gas, tight oil and heavy oil. Moreover, it plays an important role in the development of natural gas hydrate. Horizontal extension ability is one of the key indexes of horizontal well, but it is always impacted by formation properties and well structure. Therefore, a model is established to analyze the impact of formation properties and well structure as comprehensive as possible, which considers not only traditional influencing factors, like formation pressure and drilling bit parameters, but also other key factors, including cutting particle size, wellbore diameter and cross section. Based on the analysis, some advises are proposed for field application. The analysis indicates that horizontal well has stronger extension ability in the formation with low formation pressure and high fracture pressure, but it is still limited by pump pressure. Under-balanced drilling can strength the extension ability in high formation pressure by reducing drilling mud density. The natural fractures in formation should be noted when drilling long horizontal well. The extension length increases and then decreases with the cutting particle size, so cutting particle has optimal size for the horizontal extension length, which can be adjusted by the rate of penetration and rotation speed. The extension length increases first and then decreases with the gap between drilling string and hole. Considering the demand of rock breaking and cutting sweeping around drilling bit, it is not recommended to adjust the drilling bit parameters. Both the cutting bed height and drilling string eccentricity have impact on horizontal extension length by changing minimum cutting-carry pump rate and annular pressure drop. Under different combinations of above two parameters, minimum cutting-carry pump rate and horizontal extension length are determined by different factors and can be divided into three parts, including acceptable cutting bed height, cutting lifting efficiency, pump pressure and total circulation pressure loss and well bottom pressure and formation fracture pressure. The findings of this study can help for better understanding of horizontal well hydraulic extension length and optimization method.

A Multiparameter Coupled Prediction Model for Annular Cuttings Bed Height in Horizontal Wells

“…In this paper, the computational fluid dynamics software FLUENT is used to simulate the cuttings migration. The Euler multiphase flow model is used as the control model, the structured grid is used for mesh generation, and the second-order upwind scheme is used for numerical iteration [22][23][24][25][26][27].…”

Optimization of the Lateral Length of Shale-Gas Horizontal Wells Based on Geology–Engineering–Economy Integration

“…Guo Xiaole et al [5] established the hydraulic extension limit model of extendedreach wells, which showed that the formation safety density window and the maximum allowable total pressure loss were objective constraints on the hydraulic extension limit of extended-reach wells in the Liuhua Oilfield in the South China Sea. Under the existing equipment conditions, the hydraulic extension limit was mainly limited by the pump pressure in the slope-stabilizing section, and the hydraulic extension limit length of the slope-stabilizing section was 6500~7200 m. The horizontal extension length of horizontal wells were determined by different factors and could be divided into three parts, including the acceptable cutting bed height, cutting lifting efficiency, pump pressure, total circulation pressure loss, well bottom pressure, and formation fracture pressure [6]. Based on the established calculation model of the circulating pressure loss of horizontal wells, Xu Kunji et al [7] studied the lateral extension ability of horizontal wells and found that the hydraulic extension ability of horizontal sections was affected by factors such as drilling fluid density, the rated pressure of drilling pumps, the height of cutting beds, and the drilling-fluid displacement.…”

Enhancing the benefit of slide steering drilling systems in horizontal wells of unconventional reservoirs

“…A horizontal well is an important method to develop unconventional reservoirs, like shale gas (Guo et al, 2019;Lu et al, 2021), tight oil, gas hydrate (Zhang et al, 2022a), and even deep reservoirs (Zhang et al, 2022b;Cao et al, 2022). The slide steering drilling system composed of a bent positive displacement motor (PDM) and measurement while drilling (MWD) system is widely used in horizontal wells.…”

“…By alternatively applying these two modes, it can continuously implement wellpath control operations without tripping operations. Currently, longer horizontal wells are being drilled to develop unconventional oil and gas (Guo et al, 2019;Lu et al, 2021;Yu et al, 2021;Ma et al, 2022). Because the drillstring does not rotate in the slide drilling mode, the friction force on the drillstring not only decreases the weight-on-bit transmission efficiency and causes low drilling speed but also influences the horizontal extension ability (Maidla and Haci, 2004;Samuel, 2010;Zhu et al, 2019).…”