Cave scale calculating method for fracture-vug type carbonate oil and gas pools

Abstract

The invention belongs to the technical field of oil-gas field development, concretely relating to a cave scale calculating method for fracture-vug type carbonate oil and gas pools. The method comprises the following steps: A, collecting basic parameters of stratums and fluids and well pressure recovery test data; B, creating a double logarithmic curve and a semi-logarithmic curve with the pressurerecovery test data; C, finding out a starting time point and a finish time point of a straight line segment on the semi-logarithmic curve; D, calculating a slope of the straight line segment according to the semi-logarithmic curve and calculating the formation flow capacity kh according to the slope; E, finding out caviton intervals at a corresponding time interval on the semi-logarithmic curve according to the straight line segment found out by the step C; F, calculating caviton areas S according to a numerical integration method; G, calculating the volume V of a cave on the spot according to the cave volume formula. The method is highly feasible and accurate and capable of calculating the cave scale for the fracture-vug type carbonate oil and gas pools, which provides an important theoretical foundation to the oil-gas field development on the spot.

Description

technical field [0001] The invention relates to a method for calculating the scale and size of dissolved caves in fracture-cavity carbonate rock oil and gas reservoirs, belonging to the technical field of oil and gas field development. Background technique [0002] Well testing is an important means and method for understanding oil and gas reservoirs. Fracture-cavity carbonate reservoirs have various storage spaces, with large caves as the main storage space and fractures as the main seepage channels. At the same time, caves and fractures are of different sizes, and there is a huge difference, with obvious multi-scale Moreover, the distribution of caves and fractures is uneven and the continuity is poor, so the flow mechanism of fracture-cavity carbonate reservoirs is extremely complex. [0003] In terms of well testing in fractured-cavity carbonate reservoirs, predecessors have proposed various well testing mathematical models and their sample curves. Curves are often dif...

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Problems solved by technology

Fracture-cavity carbonate reservoirs have various storage spaces, with large caves as the main storage space and fractures as the main seepage channels. At the same time, caves and fractures are of different sizes, and there is a huge difference, with obvious multi-scale The distribution of caves and fractures is uneven and the continuity is poor, so the flow mechanism of fracture-cavity carbonate reservoirs is extremely complex

[0003] In terms of well testing in fractured-cavity carbonate reservoirs, predecessors have proposed various well testing mathematical models and their sample curves. Curves are often difficult to fit

[0004] At present, the theoretical research to solve the above problems mainly has two aspects: one is based on the conventional dual-medium seepage theory, the flow mechanism and mathematical models are mainly focused on the fractured medium system, the hole-fracture-matrix system and the fracture-matrix medium systems, but few studies involving large cave-fracture media systems

The second is to directly use the combination of pipe flow and open channel flow in fluid mechanics to describe it, but it cannot explain the relevant formation parameters well

These two methods are difficult to solve the problem of multi-parameter calculation and accurate curve fitting in well test interpretation of fractured-cavity reservoirs, resulting in no accurate and reliable well test interpretation results, which greatly increase the development plan of fractured-vuggy carbonate rocks. great difficulty and uncertainty

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