Pushing the Boundaries Through Successful Delivery of Highly Challenging ERD Well in Offshore East Java, Indonesia

With the far-reaching reservoir target coupled with other surface constraint including fix well slot coordinate and pre-determined conductor size, the longest well with 2.5 ERD Index in Offshore East Java was pioneered. The team has big task in hand to ensure all aspect of ERD well engineering and construction are being addressed properly within the fast-paced time frame given. One of the approaches strategized by the team is to split the high angle big hole size long interval of middle section into two casing string which was not the common architecture applied in the other offset wells. The objective was to ensure that the middle section of the well will not be compromised and avoid complication in the deeper section of the well. Worth to mention that the middle section consists combination of challenging lithology that deserve the right solution to avoid unwanted problem. There are highly kartsitified carbonate formation, shale and sand interbedded formation, and thick time dependent shale formation. To mitigate the challenges previously mentioned, intermediate section which is normally drilled and isolated with 17-1/2" hole × 13-3/8" casing in previous wells, now separated into two sections which require enlargement: 17-1/2" to 20" and 14-3/4" to 17-1/2". This paper focuses on 14-3/4" × 17-1/2" which is the most challenging underreaming operation in this well and the first of its kind in this field application. Adding to the fact that the inclination reach 75 degree in this section, SOBM and RSS BHA are deployed to mitigate the torque and drag issue. State of the art modelling tool is also used by team to define effectively match BHA and drilling parameter with minimal lateral vibration and stick slip for this section Apart from drilling stage, the enlarged hole size requires a condition to have uncommon casing size and specification, 16" intermediate semi flush liner connection and 13-3/8" full flush intermediate casing connection to ensure sufficient annular area and less restriction during running to bottom. The relentless effort to secure one the most critical ERD well construction phase has really paid off by allowing the next phase of operation to be executed as per plan thus assuring the overall well objective is met.

Solution of Collinearity Problem in Two-Dimensional Electrical Resistivity Tomography using Wenner Array

Two-dimensional electrical resistivity tomography (2-D ERT) is one of the most common geophysical tools employed to satisfy the ever-growing need for obtaining subsurface information. Most of the conventional electrode arrays used for 2-D ERT survey are built with the theoretical assumption that the survey lines are straight to guarantee four collinear electrodes at every point of measurement. However, due to surface constraint associated with most survey areas, it is rarely possible to conduct a two-dimensional resistivity survey on a straight line. Therefore, 2-D ERT survey conducted on a surface constraint field requires shifting one or more electrodes off the survey line, which contrasts with the underlying assumption. Consequently, the result might be prone to false anomalies. Thus, this study aimed to device a new approach that could mitigate the false anomalies posed by non-collinearity of electrodes in 2-D ERT result. In view of this, ABEM Terrameter SAS4000 using Wenner array configuration was adopted for the survey. The data was acquired with all electrodes inline and one or more electrodes offline at stepwise distances, respectively. Based on the result obtained, the new approach mitigates the offline electrodes effect, as the inverse resistivity tomograms resolves the geometries of the true model reasonably well. More so, it has high R-value >90% which is an indication of proximity to the true model. Hence, it is concluded that the new approach is effective in mitigating offline electrode effect on a 2-D ERT result.

A Hypothesis on the Origin of Old Chinese Pharyngealization (上古漢語咽化聲母來源的一個假設)

It is proposed that oc pharyngealized onset consonants—that is, ‘type-A’ onset consonants—arose out of Proto-Sino-Tibetan plain consonants followed by geminate vowels separated by a pharyngeal fricative. When the first copy of the geminate vowel fell, the initial consonants formed clusters with the pharyngeal fricative, evolving into the oc pharyngealized consonants we reconstruct. In the Kuki-Chin branch of Tibeto-Burman, the pharyngeal fricative fell, and long vowels resulted. This proposal supposes a statistical correlation between Kuki-Chin long vowels and oc type-A words on the one hand, and between Kuki-Chin short vowels and oc type-B words on the other, as originally proposed by S. Starostin. A significant statistic bearing on forty-three probable Chinese-Kuki-Chin cognates supports this correlation. Thus reconstructed, a precursor language of Proto-Sino-Tibetan was aligned with Proto-Austronesian and Proto-Austroasiatic in exhibiting a surface constraint against monomoraic free words: by that constraint, the vowel of an underlying monosyllable was realized as a geminate with an intervening parasitic consonant such as a glottal stop or a pharyngeal fricative, while the vowels of a disyllable remained nongeminate. After reduction of disyllables to monosyllables, this process resulted in a pharyngealized vs. nonpharyngealized consonant distinction in oc. 論文提出對上古漢語咽化聲母（即“A類聲母”）來源的一個假設，認為咽化聲母來源於原始漢藏語的無標記輔音，並且此無標記輔音後跟隨著由咽部擦音[ʕ]分割的雙胞元音（geminate vowels）。在雙胞元音的前半部分脫落後，輔音聲母跟咽部擦音形成了複輔音。新形成的複輔音最終演變為上古漢語的咽化聲母。而在藏緬語庫基-欽（Kuki-Chin）語支中，則是咽化擦音脫落，使雙胞元音變為長元音。本文解釋了漢語與庫基-欽語中一個統計學的顯著相關性：一方面，庫基-欽語含長元音的詞與上古漢語含A類聲母的詞呈顯著相關；另一方面，庫基-欽語含短元音的詞與上古漢語含B類聲母的詞呈顯著相關，正如斯塔羅金（S. Starostin）所說。據此構擬，我們提出原始漢藏語、原始南島語與原始南亞語中的一個共同限制（constraint）：禁止在語流中出現單音拍（monomoraic）詞。在這一限制的作用下，單音節詞的單元音發生了雙胞化（germination），雙胞元音中間插入了喉塞音或咽部擦音之類的次聲輔音。而同時，雙音節詞的元音無變化。漢語經過雙音節詞的單音節化，就形成了無標記輔音與咽化輔音的音位對立。(This article is in English.)