Performance Analysis and Optimization of the Anchor Mechanism of Coupling Anchor Type Downhole Throttle

Abstract

The slip-type downhole throttle widely used now in Sulige Gas Field has the problems of complex releasing process and low retrieving success rate caused by slip seizing tubing in throttle retrieving.Therefore,a new type downhole throttle was developed,which is fixed on the gap of tubing coupling groove by means of claw anchor,with the characteristics of easy releasing,without clamping the tubing tightly,no slippage,and retrievable in one run of wireline operation.In order to improve the working performance of anchor mechanism of the new type downhole throttle,ANSYS finite element analysis software was used to establish the finite element models for anchor mechanism and tubing coupling,so as to simulate the working process of the anchoring mechanism during anchoring and retrieving.The central combination design method was used to establish the mathematical models for describing the effect of length and thickness of the jaw on the minimum retrieving force and the maximum stress on the jaw while jarring it downward.Through analysis of the effect regularity,the optimum length and thickness of the jaw were determined as 95.6 mm and 2.9 mm respectively.In this case,the better anchoring performance was obtained,the minimum retrieving force was 1.9 kN,and the maximum stress applied on the jaw during jarring downward was 732 MPa,significantly improved the performance compared with that of the original structure.The research results showed that the anchor mechanism of the new type downhole throttle was reasonable in design,and the jaw parameter combination of anchoring mechanism was optimized while ensuring the safe operation of anchor mechanism of throttle,which can provide technical support for the field application of this new downhole throttle in the future.

AAPG Datapages/Search and Discovery Article #130001© Petroleum Drilling Techniques, Issue 2, 2018