CN-116108572-B - Shale gas condensate well volume fracturing outer zone productivity contribution analysis method

CN116108572BCN 116108572 BCN116108572 BCN 116108572BCN-116108572-B

Abstract

The invention relates to a volumetric fracturing outer zone capacity contribution analysis method of a shale gas condensate well, which comprises the following steps of establishing a mathematical physical model based on a tri-linear flow theory based on complex fracture network characteristics and oil-gas two-phase flow characteristics in the shale gas condensate well fracturing development process, wherein the model is used for equivalently processing the complex fracture network of the shale gas condensate well into a fracturing modification body, the fracturing modification body comprises an artificial main fracture, a fracturing modification inner zone and a fracturing modification outer zone, performing historical fitting on the produced shale gas condensate well dynamics based on the tri-linear flow theory to obtain typical shale and fracturing fracture parameters, analyzing the boundary lengths of different fracturing modification outer zones based on the typical shale and fracturing fracture parameters, and providing reasonable well distances considering the contribution degrees of the fracturing modification outer zone capacity under the condition of different fracturing modification outer zone permeability.

Inventors

BAI YUHU
WANG SURAN
XU BINGXIANG
ZHAO ZHIGANG
SUN LICHUN

Assignees

中海石油(中国)有限公司
中海石油（中国）有限公司北京研究中心

Dates

Publication Date: 20260508
Application Date: 20221130

Claims (6)

1. The method for analyzing the volumetric fracturing outer zone productivity contribution of the shale gas condensate well is characterized by comprising the following steps of: Based on complex fracture network characteristics and oil-gas two-phase flow characteristics in the shale gas condensate well fracturing development process, establishing a mathematical physical model based on a tri-linear flow theory, wherein the model is used for equivalently treating the complex fracture network of the shale gas condensate well into a fracturing modification body, and the fracturing modification body comprises an artificial main fracture, a fracturing modification inner area and a fracturing modification outer area; performing history fitting on the produced shale gas condensate well dynamics based on a mathematical physical model of a tri-linear flow theory to obtain typical shale and fracturing fracture parameters; Based on typical shale and fracturing fracture parameters, analyzing the boundary lengths of different fracturing transformation outer zones, and under the conditions of different fracturing transformation outer zone permeability, the contribution degree of the fracturing transformation outer zones to the productivity, so as to give a reasonable well distance considering the contribution degree of the fracturing transformation outer zones; The equation for the fracture remodeled outer zone is: The fracturing reconstruction outer region is a matrix region, the Langmuir theory is used for describing the adsorption and desorption of the gas, (1) In the formula, Is Langerhans' volume; Is Langerhans pressure; is the pressure; The gas adsorption amount in the rock per unit volume; The differential equation of the seepage of the oil and gas in the fracturing reforming outer zone is as follows: gas composition: Oil component: in the formula, Is the relative permeability of the gas phase in the outer zone; Relative permeability of the oil phase in the outer region; permeability for the outer zone matrix; Porosity for the outer region matrix; saturation of the outer zone with gas; oil saturation for the outer zone; Is the viscosity of the gas; is the viscosity of crude oil; is the gas volume coefficient; Is the volume coefficient of crude oil; T is the outer zone pressure; the content of the dissolved condensate oil in the gas phase; Is Langerhans' volume; pressure of Langerhans, y is the direction of coordinates.
2. The method for analysis of volumetric frac out-of-zone capacity contribution of a shale gas condensate well of claim 1, wherein the mathematical physical model of the tri-linear flow theory is established based on the following assumptions: the shale reservoir is of horizontal equal thickness, the horizontal well is positioned in the center of the reservoir, and the crack penetrates through the whole reservoir; considering the compressibility of oil and gas, neglecting the compressibility of rock; The adsorption and desorption of the gas are subject to a Langmuir single-layer adsorption model, and the adsorption mechanism of the condensate is not clear and is not considered independently; the fluid consists of two components, namely oil and gas, the gas component only exists in the gas phase, and the oil component can exist in the oil phase and the gas phase at the same time.
3. The method of analyzing volumetric fracturing outer zone capacity contribution of a shale gas condensate well according to claim 1, wherein the fracturing reconstruction inner zone is a dual medium, the medium is regarded as a flat plate by using an unsteady mass transfer model, and the influence on the adsorbed gas content refers to the fracturing reconstruction outer zone, so that a flow equation in a matrix is as follows: gas composition: Oil component: in the formula, Is the relative permeability of the gas phase in the inner zone matrix; relative permeability of oil phase in the inner zone matrix; permeability for the inner zone matrix; porosity for the inner zone matrix; Saturation of the gas in the inner zone matrix; saturation of oil in the inner zone matrix; is the internal matrix pressure, and z is the coordinate direction.
4. The method for analysis of volumetric frac out-of-zone capacity contribution of a shale gas condensate well of claim 3, wherein the flow equation in the matrix is: gas composition: Oil component: in the formula, The relative permeability in the secondary fracture of the inner zone; the relative permeability of the oil phase in the secondary cracks of the inner zone; the permeability of secondary cracks in the inner zone; secondary fracture porosity for the inner zone; The saturation of gas in the secondary cracks of the inner zone; the saturation of oil in the secondary crack of the inner zone; the secondary fracture pressure in the inner zone; The mass of gas flowing into the unit volume of the secondary fracture from the inner zone matrix system in unit time; The mass of the gas flowing into the unit volume secondary crack from the matrix system in the inner area and the outer area in unit time is shown, and x is the coordinate direction.
5. The method for analysis of volumetric frac out-of-zone capacity contribution of a shale gas condensate well of claim 4, wherein considering fluid exchange from a frac-remodelled inner zone fracture to an artificial fracture, the percolation equation in the artificial fracture is: gas composition: Oil component: in the formula, Relative permeability in the artificial fracture; the relative permeability of the oil phase in the artificial fracture; is the permeability of the artificial crack; Is the porosity of the artificial crack; The gas saturation in the artificial crack; The saturation degree of oil in the artificial crack; is the pressure of the artificial crack; the mass of gas flowing into the artificial crack in unit volume from the secondary crack in unit time; the mass of crude oil flowing into the unit volume artificial fracture from the secondary fracture in unit time is shown, and x is the coordinate direction.
6. The method of analyzing volumetric frac out-zone capacity contribution of a shale gas condensate well of claim 4, wherein typical shale and frac fracture parameters include fracture half-length, secondary fracture permeability, inner/outer zone matrix permeability, artificial fracture conductivity, matrix block width of frac remodelled inner zone.

Description

Shale gas condensate well volume fracturing outer zone productivity contribution analysis method Technical Field The invention relates to a shale gas condensate well volumetric fracturing outer zone productivity contribution analysis method, and belongs to the technical field of oil and gas mineral exploration and development. Background Shale oil and gas fields are important mineral resources for oil and gas development, but because shale is extremely dense, the matrix permeability is tens to hundreds of nanodarcies, so that the matrix outside the fracturing modification zone is generally considered to contribute little to the yield and can be ignored. Therefore, when the reasonable well spacing of the shale oil gas well is determined, theoretical calculation and micro-seismic monitoring of the fracturing cracks are often used as the main, the fracturing cracks are simulated according to the physical properties, brittleness, ground stress and the like of the shale, and the construction design such as displacement and the like, so that the achievable half length of the fracturing cracks is determined, the influences of parameters such as the half length of the fracturing cracks, the diversion capacity, the matrix permeability and the like on the yield and the economy are analyzed by the oil reservoir engineering specialty according to an oil reservoir engineering method or a numerical simulation method, so that the theoretical optimal well spacing is optimized, the theoretical optimization design is also combined with on-site crack monitoring, and the half length of the fracturing cracks is used as the reasonable well spacing according to the form and the distribution range of the fracturing cracks monitored by the micro-seismic monitoring, but in fact, the horizontal well spacing of the shale gas in North Americ is always in the continuous optimization process according to the factors such as geology, fluid and technology. According to actual production data of the North American hawk beach condensate gas well, under the condition that the fracturing parameters are basically consistent in the same area, the yield is reduced progressively with the increase of the well spacing, as shown in figure 1, the fact that the area outside the fracturing modification area (SRV) can supply gas to the modification area is shown, so that the yield of the gas well is increased, and the oil gas progressive rate is reduced. How to evaluate the impact of areas outside the fracture reformation zone (SRV) on hydrocarbon production is an urgent issue to be addressed. Disclosure of Invention Aiming at the technical problems, the invention provides a volumetric fracturing external zone productivity contribution analysis method of a shale gas condensate well, which establishes a mathematical physical model based on a tri-linear flow theory aiming at complex fracture network characteristics and oil-gas two-phase flow characteristics in the shale gas condensate well fracturing development process, obtains typical shale and fracturing fracture parameters on the basis of history fitting of produced shale gas condensate well dynamics, and develops fracturing transformation external zone productivity contribution analysis on the basis of the typical shale and fracturing fracture parameters. In order to achieve the above purpose, the present invention adopts the following technical scheme: a shale gas condensate well volumetric fracturing outer zone productivity contribution analysis method comprises the following steps: Based on complex fracture network characteristics and oil-gas two-phase flow characteristics in the shale gas condensate well fracturing development process, establishing a mathematical physical model based on a tri-linear flow theory, wherein the model is used for equivalently treating the complex fracture network of the shale gas condensate well into a fracturing modification body, and the fracturing modification body comprises an artificial main fracture, a fracturing modification inner area and a fracturing modification outer area; performing history fitting on the produced shale gas condensate well dynamics based on a mathematical physical model of a tri-linear flow theory to obtain typical shale and fracturing fracture parameters; Based on typical shale and fracturing fracture parameters, different fracturing transformation outer zone boundary lengths are analyzed, and under different fracturing transformation outer zone permeability conditions, the contribution degree of the fracturing transformation outer zone to productivity is given out, so that reasonable well spacing considering the fracturing transformation outer zone contribution degree is provided. In the shale gas condensate well volumetric fracturing outer zone capacity contribution analysis method, preferably, the establishment of the mathematical physical model of the three-linear flow theory is based on the following assumption: the shale reservoir is