Target point adjusting method for horizontal well in thin carbonate reservoir

Abstract

The invention discloses a target point adjusting method for a horizontal well in a thin carbonate reservoir. The method comprises the following steps: taking well drilling data as reference, taking small layer comparison as the foundation, combining earthquake lateral prediction results, tracing the fluctuation of a marker bed between wells, describing the low relief structure form of each marker bed, building a fine geologic model for a low relief structure, and preparing for target entering of the horizontal well; according to the deposition characteristic and the lithological change of the reservoir, defining target point adjusting time, selecting a proper reference marker bed, and adjusting the initial target point of the horizontal well according to the practical altitude value of a drilled marker bed; and building a target entering stratigraphical correlation method of the horizontal well, and further thinning the low relief structure form of the marker bed and amending the target point according to the stratigraphical correlation result. Through the adoption of a conventional geological guiding technology, the method has the advantages that the accurate target entering of the thin carbonate reservoir is realized, and the developing effect of the horizontal well is guaranteed.

Description

technical field [0001] The invention relates to the technical field of natural gas exploitation, in particular to a method for adjusting target points of horizontal wells in thin carbonate rock reservoirs. Background technique [0002] In the development of horizontal wells in thin reservoirs, advanced near-bit geosteering tools are mainly used at home and abroad to ensure accurate horizontal well targeting. At present, there is no such technology and related equipment in China, and the horizontal well development of this type of reservoir can only be carried out by contractors using instruments of foreign companies (such as the EcoScope series of Schlumberger Company and the INTEQ series of Baker Hughes Company). Due to technology monopoly and high service costs, large-scale horizontal well development for low-permeability and low-abundance thin-bed carbonate gas reservoirs has high costs and low economic benefits, making many gas reservoirs of the same type worthless. [...

AI Technical Summary

Problems solved by technology

Due to technical monopoly and high service costs, large-scale horizontal well development for low-permeability and low-abundance thin-bed carbonate gas reservoirs has high costs and low economic benefits, making many gas reservoirs of the same type worthless

[0003] Using conventional mud logging and drilling technology (MWD geosteering measurement point is about 12m away from the drill bit), the geosteering of horizontal wells in thin reservoirs often leads to a low target success rate and a large waste of drilling footage

In addition, the development of horizontal wells in karst carbonate reservoirs not only has the particularity of the main reservoir being thin, but also has technical or professional difficulties or limitations. The impact resolution is low, and it is difficult to identify small-amplitude structures; during the implementation of horizontal wells, it is difficult to connect various disciplines such as geology, seismic, drilling, and mud logging, which makes it difficult to reach a consensus on the interpretation of the same drilling phenomenon in different disciplines

[0004] The existing horizontal well targeting technology has the following characteristics: (1) Horizontal well geosteering instruments are more advanced. Generally, for the development of horizontal wells in thin reservoirs, near-bit instruments are mainly used, such as Dagangcheng, Daqing oil lease Schlumberger, Baker Hughes company geosteering The instrument can complete the reservoir geosteering with a thickness of 4.0m; (2) The gas reservoir is buried shallower (about 2000m), and the overlying stratum of the reservoir is less, so the geosteering of horizontal wells is less difficult; (3) It is mainly used in sandstone oil and gas reservoirs, Carbonate gas reservoirs are rarely used, and the technical operability is not strong

The existing technology has been widely used in Daqing, Dagang, Xinjiang and other oilfields, but it is difficult to solve the problem of water in deep buried (3500.0m-4500.0m), low permeability, thin layer (1.0m-6.0m) carbonate gas reservoirs. Hirai target problem

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