With the increasing safety standards for offshore oil and gas， the efficiency and cost challenges of trenching for submarine pipeline protection are becoming more complex due to varying seabed substrates. Traditional jet trenching methods are inefficient in hard soil and rocky reef areas. This paper systematically introduces the operational practices of a dynamically positioned vessel equipped with a large plough-type trencher for a pipeline protection project in a shallow-water area in northern Weizhou. It focuses on analyzing the adaptability of this plow-type trenching machine to complex geological conditions ranging from loose sandy soil to strongly weathered basalt. The study elaborates on a trenching drag force prediction method based on soil shear strength and the dynamic control strategies implemented during actual operations. By comparing the theoretical drag force curve with field operational data， the effectiveness of parameter presetting is validated. This paper also summarizes key technical measures such as monitoring solutions， cable management， and emergency abandonment in shallow water with low visibility conditions， providing technical solutions and data references for post-protection trenching operations of submarine pipelines in similar shallow water and complex geological environments.