琼东南盆地中央峡谷“深海一号”大气田周缘成藏条件与滚动勘探成效

为探明琼东南盆地中央峡谷“深海一号”大气田的地质储量，推动该大气田的可持续开发，创新性地将滚动勘探技术引入中央峡谷深水天然气勘探。搜索该区5个潜力区块开展了滚动勘探，优选成藏条件优越且能够动用控制地质储量层位的块4，针对莺歌海组T₂₉B、T₂₉E砂体以及黄流组HL-Ⅰ_上、HL-Ⅲ、HL-Ⅳ气组开展了成藏条件研究；并通过与周边已钻井成果及成藏规律的类比，重点研究了块4的圈闭、储层沉积、油气运聚等成藏条件。块4黄流组和莺歌海组T₂₉E砂体均为被中央峡谷水道壁与峡谷内部后期弱振幅泥质水道联合封闭形成的岩性圈闭，而莺歌海组T₂₉B砂体为峡谷背景下的海底扇局部高点形成的背斜圈闭；通过振幅属性砂体刻画技术、正演模拟技术，落实了块4黄流组和莺歌海组目的层中好的储盖组合；油气通过底辟、高角度裂缝和微裂缝等垂向运移通道运移至目的层圈闭中，而圈闭的顶底板有效性较好，从而起到很好的保存油气的作用。根据各成藏要素落实了资源量参数及潜在资源量，开展深水滚动探井部署，引入深水定向井钻探技术，部署L17-10d井落实含气层系和储量规模，取得了较好的钻探效果。L17-10d井在T₂₉B、T₂₉E砂体及HL-Ⅲ气组钻遇纯气层，气层垂厚近45 m，落实探明地质储量近70亿立方米；证实了中央峡谷深水区的成藏规律，为周边区域滚动勘探指明了方向；同时促进了部分难动用天然气探明地质储量与控制地质储量的动用，为深海一号大气田后续可持续开发提供了有力保障。

Accumulation conditions and rolling exploration results in the periphery of "Deep Sea No. 1" giant gas field in central canyon of Qiongdongnan Basin

In order to explore high-quality proven geological reserves for the "Deep Sea No.1" giant gas field in the central canyon of the Qiongdongnan Basin and promote the sustainable development of the giant gas field, the rolling exploration technology is innovatively introduced into the deep-water natural gas exploration in the central canyon. The main gas-bearing strata such as the Upper Miocene Huangliu Formation and the Pliocene Yinggehai Formation on the periphery of mature exploration area of the gas field are studied. Five potential blocks are searched for rolling exploration, and Block 4 with superior reservoir forming conditions and the ability to control geological reserves is selected. The reservoir forming conditions of T29B and T29E sand bodies in the Yinggehai Formation, upper HL-Ⅰ, HL-Ⅲ and HL-Ⅳ gas groups in the Huangliu Formation are studied. By analogy with drilling data and accumulation rules of the surrounding wells, the accumulation conditions such as trap, reservoir deposition and oil and gas migration and accumulation of Block 4 are studied. The T29E sand bodies of the Huangliu Formation and the Yinggehai Formation in Block 4 are all lithologic traps formed by the joint closure of the central canyon channel bank and the weak-amplitude muddy channel in the later stage of the canyon. The T29B sand body is an anticline trap formed by the local high point of the submarine fan under the canyon background. Through the amplitude attribute sand body characterization and forward modeling, the reservoir-seal combination of the target layer of the Huangliu and Yinggehai formations in Block 4 is well implemented. The vertical migration modes such as diapirs, high-angle fractures and micro-fractures are migrated to the target layer traps, and the effectiveness of the top and bottom plates of the traps is good, thus playing a good role in preserving oil and gas. According to the accumulation factors, the resource parameters and potential resources are implemented, and the deployment of deep-water rolling exploration wells is carried out. The deep-water directional drilling technology is innovatively introduced, and the well L17-10d is deployed to implement the gas-bearing strata and reserve scale as much as possible, and good drilling results are achieved. The well L17-10d encountered a pure gas layer in the T29B, T29E sand bodies and the HL-Ⅲ gas group. The vertical thickness of the gas layer was nearly 45 m, and the proven geological reserves were nearly 7 billion cubic meters. It further confirmed the accumulation law of the deep water area of the central canyon, pointed out the direction for the rolling exploration of the surrounding area, promoted the production of proven geological reserves and controlled geological reserves of some difficult-to-produce natural gas, and provided a strong guarantee for the subsequent sustainable development of the "Deep Sea No.1" giant gas field.