Research on an Lost Circulation Zone Location Method Based on Transient Pressure Wave

Abstract

Accurately identifying the location of loss zone after lost circulation is the key to subsequent plugging operation. In view of the difficulty of identifying the location of lost circulation zone, a method of identifying the location of loss zone by transient pressure wave signal is proposed. When lost circulation occurs, transient back pressure is applied to the wellhead at the surface choke manifold to produce transient pressure wave. The transient pressure wave propagates downward from the wellhead. The propagation process of transient pressure wave in an annulus system is analyzed, and the position of loss zone is determined according to the change of pressure signal at the choke manifold. Based on the simulation of this method, relevant experiments are also carried out. Aiming at the problem of excessive noise of the pressure wave signal collected in the experiment, variational modal decomposition (VMD) is used to decompose the signal into multiple band-limited intrinsic mode function (BIMF) components. Combined with a Hilbert spectrum, the time–frequency characteristics and energy distribution of each BIMF component are analyzed in turn. The main frequency component is selected to reconstruct the signal to achieve the denoising effect. On this basis, a wavelet modulus maxima method is used to decompose the denoised signal, extract the characteristic points of the signal, identify the loss circulation information in the signal, and then identify the thief zone position by a time–domain method. Through experimental verification, the existence of loss zone will affect the change trend of pressure wave; a VMD–wavelet modulus maxima algorithm can effectively remove the noise of the pressure wave signal and locate the pressure change point. The experimental recognition error range of this method is 0.10–9.22%, which has certain guiding significance for field application.

A review of tracer testing techniques in porous media specially attributed to the oil and gas industry

“…The reasons for fluid loss could bea) There could arise a case where none of the tracers reaches the surface through the production well. This could be attributed to the fact that there might be fractures or high permeability formations or regions that could have swayed the tracer-induced fluid into an altogether different area that is not covered in the sampling program (R. Zhang et al 2021). b) Fractures or high permeability channels could also lead to insignificant pressure buildup at the injector even after the entire calculated fluid volume has been injected.…”

Research on spectral method of lost circulation layer located by transient pressure wave

“…This method only requires adding valves and pressure sensors at the equipment outlet under test, characterized by simple construction and fast and effective response. Many scholars have continued and studied the method from the time domain, [28][29][30] the frequency domain, [31][32][33][34][35] and signal processing. 36,37 In 2003, Ferrante applied the impulse response method to solve the control equations for transient flow in pressure pipelines directly in the frequency domain and through the expressions for the pressure spectrum at the downstream end of a single pipe system to analyze the pipeline leakage system.…”