CN-121993161-A - Method for determining permeability and porosity of karst cave main body in interlayer karst region

CN121993161ACN 121993161 ACN121993161 ACN 121993161ACN-121993161-A

Abstract

The invention provides a method for determining permeability and porosity of a karst cave main body in an interlayer karst region, which comprises the steps of collecting study region data and determining a single well belonging to a single fracture-cave body; the method comprises the steps of performing single well logging interpretation, determining inner zone permeability and outer zone permeability of the single well logging interpretation, establishing a first relation model by using the inner zone permeability and the outer zone permeability, establishing a broken zone logging interpretation model by using research zone data, performing broken zone permeability logging interpretation, and obtaining karst cave main body permeability by using the first relation model and the broken zone permeability. The porosity determination method comprises the steps of determining the permeability of the karst cave main body by adopting the permeability determination method, establishing a second relation model by utilizing research area data, and obtaining the porosity of the karst cave main body through the second relation model and the permeability of the karst cave main body. The invention accurately assigns the porosity and permeability of the interlayer karst fracture-cavity body and provides important reservoir physical parameters for efficient development of fracture-cavity carbonate reservoirs.

Inventors

LI ZHUZHENG
LI HONGXI
DENG YUERUI
WU BAIYI
TIAN HENG
WANG JIAHUI
XIA HUIPING
HUANG TINGTING
Xue Taofeng

Assignees

中国石油天然气集团有限公司
中国石油集团川庆钻探工程有限公司

Dates

Publication Date: 20260508
Application Date: 20241108

Claims (10)

1. The method for determining the permeability of the karst cave main body in the interlayer karst region is characterized by comprising the following steps of: Collecting study area data, and determining single wells belonging to a single fracture-cavity body; Performing single well test interpretation, and determining the permeability of an inner zone and the permeability of an outer zone of the single well test interpretation; Establishing a first relation model by using the permeability of the inner zone and the permeability of the outer zone, establishing a broken zone logging interpretation model by using the information of the research zone, and performing broken zone permeability logging interpretation to obtain broken zone permeability after logging interpretation; and obtaining the permeability of the karst cave main body through the first relation model and the permeability of the fracture zone after well logging interpretation.
2. The method of claim 1, wherein the single well test interpretation comprises single well test interpretation from pressure recovery data of a single fracture-cavity body well of the research area.
3. The method of claim 1, wherein the inner zone permeability of the well test interpretation corresponds to the karst cave body permeability of a single fracture cave body and the outer zone permeability of the well test interpretation corresponds to the fracture zone permeability of a single fracture cave body.
4. The method of claim 1, wherein the first relational model comprises the following equation 1: formula 1:K karst cave main body ＝a*K Crushing belt b ; wherein K is permeability, mD, and a and b are constants.
5. The method of claim 1, wherein the study area data comprises at least one of experimental, logging, well logging, seismic, dynamic monitoring, and pressure recovery data.
6. The method of claim 1, wherein the establishing a fractured zone log interpretation model using the zone of interest data comprises establishing a fractured zone log interpretation model using log or imaging well data.
7. The method for determining the porosity of the karst cave main body in the interlayer karst region is characterized by comprising the following steps of: determining the karst cave main body permeability by adopting the interlayer karst region karst cave main body permeability determining method according to any one of claims 1-6; and establishing a second relation model by utilizing research area data, and obtaining the porosity of the karst cave main body through the second relation model and the permeability of the karst cave main body.
8. The method of claim 7, wherein creating a second relationship model using the study area data comprises simulating the formation of the karst cave body from the study area data, measuring the porosity and permeability, fitting the porosity and permeability, and creating a relationship model of the karst cave body porosity and permeability.
9. The method of claim 8, wherein simulating formation of the karst cave body from the study area data comprises simulating formation of the karst cave body from a log interpretation porosity and permeability of the karst cave body with log, a field outcrop measured karst cave body porosity and permeability, or an object model method.
10. The method of claim 7 or 8, wherein the second relational model comprises the following equation 2: Formula 2: por karst cave main body ＝c ln(K karst cave main body ) +d; Wherein, por represents porosity, m 3 /m 3 , K represents permeability, mD, c and d are constants.

Description

Method for determining permeability and porosity of karst cave main body in interlayer karst region Technical Field The invention relates to the field of oil and gas field exploration, in particular to a method for determining the permeability of a karst cave main body in an interlayer karst area and a method for determining the porosity of the karst cave main body in the interlayer karst area. Background Carbonate reservoirs are one of the most important exploration and development fields in the strategic layout of energy. The carbonate hydrocarbon reservoirs found at present mainly comprise a down-the-mine karst carbonate hydrocarbon reservoir, an interlaminar karst carbonate hydrocarbon reservoir or a controlled-release karst carbonate hydrocarbon reservoir. The interlayer karst carbonate rock oil and gas reservoir is influenced by the long-term corrosion of the water body of the underground river, the scale of forming karst cave is huge and can reach more than 600m, and the water falling cave can be formed and can reach several kilometers or tens kilometers in length. The well drilling and the well drilling are in contact with the erosion seam hole body, serious leakage or emptying occurs, the well drilling is difficult to continue and finish drilling in advance, well logging cannot be performed, therefore, the well drilling and the inter-layer karst seam hole body often have no logging data, the filling degree and the filling mode of different filling materials in the inter-layer karst seam hole body are different, and the reservoir heterogeneity and the reservoir physical parameter porosity and the permeability are difficult to obtain. The interlayer karst slot body is subjected to the action of the overlying pressure, and the upper part of the karst slot and the surrounding stratum can form a broken belt under the action of the stress, so that the interlayer karst slot body is divided into three belts, namely a karst slot body, a broken belt and surrounding rocks. The surrounding rock is relatively compact, cracks are underdeveloped, mainly the biological clastic limestone and dolomite limestone are formed by karst expansion on the basis of raw scraps and Bai Yunjing holes, the karst expansion is mostly elliptical or irregular round, the aperture is 2-10mm, the maximum aperture can reach 10cm, the surrounding rock is distributed in a lump, a layer or a strip shape on the plane, well drilling is generally free of leakage or small in leakage, the influence on well drilling is small, the broken belt is influenced by multi-stage structural movement, the broken belt collapses on the roof of the multiple stages of development, the broken belt is eroded along the cracks under the action of groundwater to form small-scale eroded holes, the well drilling is easy to leak, the leakage amount is small, the well drilling can be smoothly performed, the karst main body takes half-filled or unfilled as a main body, the height of the karst main body exceeds 3m, the width exceeds 6m, serious leakage or emptying is easy to occur when the well drilling is encountered on the karst main body, the well drilling cannot be sustained, and the well drilling is finished in advance. When the karst slot hole body between the layers is drilled, surrounding rock and broken zones of the karst slot hole body between the layers can be drilled completely, but the karst hole body is difficult to drill completely, and reservoir physical parameters of the karst hole body are critical to reservoir evaluation and development strategy formulation. At present, the porosity of the fracture-cavity body is determined through the porosity inversion of the fracture-cavity body mainly through well-vibration combination, but the seismic data is affected by the quality and the precision of the seismic data, and the porosity inversion result has large deviation from reality and cannot meet the requirements. Therefore, the method for determining the permeability and the porosity of the karst region karst cave main body, which can be used for fine characterization of the fracture-cave type carbonate reservoir, has important significance. The Chinese patent application No. CN202211351425.8, entitled "determination method of carbonate reservoir permeability" discloses a determination method of carbonate reservoir permeability, which comprises the steps of firstly establishing a reservoir total porosity model by using a coring well logging curve and core analysis data, constructing an inter-grain porosity and permeability master control relation, then calibrating and establishing a reservoir non-permeability equivalent porosity model on the logging curve by using non-permeability equivalent porosity, establishing a reservoir equivalent porosity correction coefficient model by analyzing the relationship between the core non-permeability equivalent porosity and the equivalent porosity correction coefficient, finally realizing calculation of reservoir equival