Evaluation And Development About The Belt Of The Thin-Stratum Heavy Oil By Yielding Horizontal Wells In The Western Slope West Depression Liaohe Oilfield

This paper is a technical summary on the evaluation and development of the thin-stratum heavy oil in the Western slope, west Depression, Liaohe oilfield. It presented the distribution and the control factors of the thin-stratum heavy oil reservoir by analyzing the regional geology background and by using the high-resolution sequence theory and the hydrocarbon accumulation system theory. The technologies about horizontal wells will be introduced to the exploration and development in thin-stratum heavy oil reservoir. This paper is a meaningful attempt on the exploration and development of the difficult recoverable reserves of heavy oil.The following results were achieved in this paper:1. The high-resolution sequences framework of shahejie formation has been established and divided into two 3rd order sequences and four 4th order sequences and 9 5th order sequences. Several sedimentary micro faces have been recognized within the high-resolution sequences framework, such as channels, bars and so on. Two large scale fan deltas were identified.The sedimentary micro faces mapping of the 4th order sequence revealed the xibaqian fan delta is bigger in this area and the lateral change of micro faces and sand thickness.2. According to fracture System research, all the faults were divided into three groups and the work area was divided into two parts: the internal slope and the basin margin. According to the similarity of causes and features, the structure was subdivided into six block-areas. In accordance with the genetic type, the traps were classified. All the traps were divided into 3 major categories, such as structure traps, formation traps and rock traps. The main trap type is structure in this area. Structure traps can be subdivided into block traps, broken-nose traps, broken-anticline traps. And they mainly distribute in the internal slope. the main formation trap is the unconformity trap which mainly distributes in the basin margin. Rock trap is seldom in this area.3. The distribution characters of the thin-stratum reservoirs were described and three major areas were identified to be explored. Started from two different modes in this district, all sorts of factors was analyzed which influence and control the distribution of heavy oil, such as structure, deposition, fracture and reservoir conditions. Those factors which control the distribution of heavy oil in the thin-stratum reservoir were focused. And the characters of the unconformity reservoir was tried to be told in this paper, too.4. Through analyzing the superiority of the horizontal wells which compare to the vertical wells, the horizontal wells were selected as the style to evaluate and develop these reservoirs. By applying numerical simulation methods, the minimum stratum thickness was demonstrated. So the research of exploration and development about horizontal wells was carried out in the three areas.